gnu-smalltalk-common 3.2.4-2.1 / usr / share / gnu-smalltalk / kernel / FilePath.st

"======================================================================
|
|   FilePath Method Definitions
|
|
 ======================================================================"

"======================================================================
|
| Copyright 2008, 2009 Free Software Foundation, Inc.
| Written by Paolo Bonzini.
|
| This file is part of the GNU Smalltalk class library.
|
| The GNU Smalltalk class library is free software; you can redistribute it
| and/or modify it under the terms of the GNU Lesser General Public License
| as published by the Free Software Foundation; either version 2.1, or (at
| your option) any later version.
| 
| The GNU Smalltalk class library is distributed in the hope that it will be
| useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
| General Public License for more details.
| 
| You should have received a copy of the GNU Lesser General Public License
| along with the GNU Smalltalk class library; see the file COPYING.LIB.
| If not, write to the Free Software Foundation, 59 Temple Place - Suite
| 330, Boston, MA 02110-1301, USA.  
|
 ======================================================================"



Object subclass: FilePath [
    <category: 'Streams-Files'>
    <comment: 'I expose the syntax of file names, including paths.  I know how to
manipulate such a path by splitting it into its components.  In addition,
I expose information about files (both real and virtual) such as their
size and timestamps.'>

    FilePath class >> append: fileName to: directory [
	"Answer the name of a file named `fileName' which resides in a directory
	 named `directory'."

	| dir fname |
	<category: 'file name management'>
	dir := directory.
	fname := fileName.
	Directory pathSeparator == $\ ifTrue: [
	    dir := dir copyReplacing: $/ withObject: $\.
	    fname := fname copyReplacing: $/ withObject: $\ ].
	dir isEmpty ifTrue: [^fname].
	fname isEmpty ifTrue: [
	    SystemExceptions.InvalidArgument signalOn: fname
		reason: 'empty filenames are invalid' ].
	Directory pathSeparator == $\ 
	    ifFalse: [(fname at: 1) isPathSeparator ifTrue: [^fname]]
	    ifTrue: 
		[(fname at: 1) isPathSeparator 
		    ifTrue: 
			[^(dir size >= 2 and: [(dir at: 2) = $:]) 
			    ifTrue: ['%1:%2' % {dir first.  fname}]
			    ifFalse: [fname]].
		(fname size >= 2 and: [(fname at: 2) = $:]) ifTrue: [^fname]].
	^(dir at: dir size) isPathSeparator 
	    ifTrue: [dir , fname]
	    ifFalse: [dir , Directory pathSeparatorString , fname]
    ]

    FilePath class >> extensionFor: aString [
	"Answer the extension of a file named `aString'.  Note: the extension
	 includes an initial dot."

	<category: 'file name management'>
	| index str |
	aString isEmpty ifTrue: [^''].
	str := aString.
	Directory pathSeparator = $\ ifTrue: [
	    str := str copyReplacing: $/ withObject: $\ ].
	index := str findLast: 
			[:each | 
			each = Directory pathSeparator ifTrue: [^''].
			each = $.].

	"Special case foo, .foo and /bar/.foo, all of which have no extension"
	index <= 1 ifTrue: [^''].
	(str at: index - 1) = Directory pathSeparator ifTrue: [^''].
	^str copyFrom: index
    ]

    FilePath class >> stripExtensionFrom: aString [
	"Remove the extension from the name of a file called `aString', and
	 answer the result."

	<category: 'file name management'>
	| index str |
	aString isEmpty ifTrue: [^''].
	str := aString.
	Directory pathSeparator = $\ ifTrue: [
	    str := str copyReplacing: $/ withObject: $\ ].
	index := str findLast: 
			[:each | 
			each = Directory pathSeparator ifTrue: [^str].
			each = $.].

	"Special case foo, .foo and /bar/.foo, all of which have no extension"
	index <= 1 ifTrue: [^str].
	(str at: index - 1) = Directory pathSeparator ifTrue: [^str].
	^str copyFrom: 1 to: index - 1
    ]

    FilePath class >> stripPathFrom: aString [
	"Remove the path from the name of a file called `aString', and
	 answer the file name plus extension."

	<category: 'file name management'>
	| index str |
	aString isEmpty ifTrue: [^''].
	str := aString.
	Directory pathSeparator = $\ ifTrue: [
	    str := str copyReplacing: $/ withObject: $\ ].
	index := aString findLast: [:each | each = Directory pathSeparator].
	^str copyFrom: index + 1
    ]

    FilePath class >> pathFor: aString ifNone: aBlock [
	"Determine the path of the name of a file called `aString', and
	 answer the result.  With the exception of the root directory, the
	 final slash is stripped.  If there is no path, evaluate aBlock and
	 return the result."

	<category: 'file name management'>
	| index str |
	str := aString.
	Directory pathSeparator = $\ ifTrue: [
	    str := str copyReplacing: $/ withObject: $\ ].
	index := str findLast: [:each | each = Directory pathSeparator].
	index = 0 ifTrue: [^aBlock value].
	index = 1 ifTrue: [^Directory pathSeparatorString].
	^str copyFrom: 1 to: index - 1
    ]

    FilePath class >> pathFor: aString [
	"Determine the path of the name of a file called `aString', and
	 answer the result.  With the exception of the root directory, the
	 final slash is stripped."

	<category: 'file name management'>
	^self pathFor: aString ifNone: ['']
    ]

    FilePath class >> stripFileNameFor: aString [
	"Determine the path of the name of a file called `aString', and
	 answer the result as a directory name including the final slash."

	<category: 'file name management'>
	| index str |
	aString isEmpty ifTrue: [^'./'].
	str := aString.
	Directory pathSeparator = $\ ifTrue: [
	    str := str copyReplacing: $/ withObject: $\ ].
	index := str findLast: [:each | each = Directory pathSeparator].
	index = 0 ifTrue: [^'./'].
	index = 1 ifTrue: [^Directory pathSeparatorString].
	^str copyFrom: 1 to: index
    ]

    FilePath class >> isAbsolute: aString [
        "Answer whether aString is an absolute ptah."

	(aString at: 1) isPathSeparator ifTrue: [ ^true ].
	Directory pathSeparator == $\ ifFalse: [ ^false ].
	"Windows paths starting X:/ are absolute"
	^aString size >= 3 and: [
		 (aString at: 2) = $: and: [(aString at: 3) isPathSeparator]]
    ]

    FilePath class >> fullNameFor: aString [
	"Answer the full path to a file called `aString', resolving the `.' and
	 `..' directory entries, and answer the result.  `/..' is the same as '/'."

	<category: 'file name management'>
	| path canonical result isWindows |
	isWindows := Directory pathSeparator == $\.
	"Windows paths starting X:/ are absolute"
	path := OrderedCollection new.
	(self isAbsolute: aString)
	    ifFalse: 
		[path addAll: (Directory workingName subStrings: Directory pathSeparator)].

	"A Windows path may contain both / and \ separators. Clean it up
	 to allow easy parsing"
	canonical := Directory pathSeparator = $/ 
		    ifTrue: [aString]
		    ifFalse: [aString copyReplacing: $/ withObject: $\].
	(canonical subStrings: Directory pathSeparator) do: 
		[:each | 
		each = '.' 
		    ifFalse: 
			[each = '..' 
			    ifTrue: [path isEmpty ifFalse: [path removeLast]]
			    ifFalse: [path add: each]]].
	path isEmpty ifTrue: [^Directory pathSeparatorString].
	result := path inject: ''
		    into: [:old :each | old , Directory pathSeparatorString , each].

	"Remove initial / from /C:/"
	(isWindows and: 
		[result size >= 4 and: 
			[(result at: 1) isPathSeparator 
			    and: [(result at: 3) = $: and: [(result at: 4) isPathSeparator]]]]) 
	    ifTrue: [^result copyFrom: 2].

	"Restore UNC paths."
	(isWindows and: [(aString at: 1) isPathSeparator and: [
		(aString at: 2) isPathSeparator]])
	    ifTrue: [^'\', result].

	^result
    ]

    FilePath class >> pathFrom: srcName to: destName [
	"Answer the relative path to destName when the current
	 directory is srcName's directory."
	<category: 'file name management'>
	^self computePathFrom: (File fullNameFor: srcName asString)
	    to: (File fullNameFor: destName asString)
    ]

    FilePath class >> computePathFrom: srcName to: destName [
	<category: 'private'>
	| src dest srcCanon destCanon srcUNC destUNC path isUnix |
	"A Windows path may contain both / and \ separators. Clean it up
	 to allow easy parsing"
	isUnix := Directory pathSeparator = $/.
	srcCanon := isUnix
		    ifTrue: [srcName]
		    ifFalse: [srcName copyReplacing: $/ withObject: $\].
	destCanon := isUnix
		    ifTrue: [destName]
		    ifFalse: [destName copyReplacing: $/ withObject: $\].

	src := srcCanon subStrings: Directory pathSeparator.
	dest := destCanon subStrings: Directory pathSeparator.

	src := src asOrderedCollection.
	dest := dest asOrderedCollection.

	src removeLast.
	dest isEmpty ifTrue: [dest addLast: ''].

	"\abc\def and \\abc\def are different!"
	srcUNC := isUnix not and: [ srcCanon startsWith: '\\' ].
	destUNC := isUnix not and: [ destCanon startsWith: '\\' ].

	path := (src isEmpty or: [src first = dest first and: [srcUNC = destUNC]])
	    ifFalse: [
	        srcUNC ifTrue: [ src addFirst: '' ].
	        destUNC ifTrue: [ dest addFirst: '' ].

		"Don't prepend a \ if the destination path has a disk letter."
		(isUnix or: [ (dest first at: 2 ifAbsent: [ nil ]) ~= $: ])
		    ifTrue: [OrderedCollection with: '']
		    ifFalse: [OrderedCollection new]]
	    ifTrue: 
		[[src isEmpty or: [dest size = 1 or: [src first ~= dest first]]] 
		    whileFalse: 
			[src removeFirst.
			dest removeFirst].
		src collect: [:each | '..']].

	path addAllLast: dest.
	^path fold: [:a :b | a , Directory pathSeparatorString , b]
    ]

    asFile [
	"Answer the receiver."

	<category: 'converting'>
	^self
    ]

    displayOn: aStream [
	"Print a representation of the receiver on aStream."

	<category: 'printing'>
	| name string |
	name := self asString.
	(name anySatisfy: [:each | '"(){}[]$\<>#'' `' includes: each]) 
	    ifFalse: 
		[aStream nextPutAll: name.
		^self].
	string := Directory pathSeparator = $/ 
		    ifTrue: ['''%1''' % {name copyReplaceAll: '''' with: '''\'''''}]
		    ifFalse: [
			{'"'.
			name.
			'"'} join].
	aStream nextPutAll: string
    ]

    printOn: aStream [
	"Print a representation of the receiver on aStream."

	<category: 'printing'>
	aStream
	    nextPut: $<;
	    print: self class;
	    space;
	    display: self;
	    nextPut: $>
    ]

    mode [
	"Answer the permission bits for the file identified by the receiver"

	<category: 'accessing'>
	self subclassResponsibility
    ]

    size [
	"Answer the size of the file identified by the receiver"

	<category: 'accessing'>
	self subclassResponsibility
    ]

    mode: anInteger [
	"Set the permission bits for the file identified by the receiver to be
	 anInteger."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    owner: ownerString group: groupString [
	"Set the owner and group of the file identified by the receiver to be
	 aString."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    group: aString [
	"Set the group of the file identified by the receiver to be aString."

	<category: 'accessing'>
	self owner: nil group: aString
    ]

    owner: aString [
	"Set the owner of the file identified by the receiver to be aString."

	<category: 'accessing'>
	self owner: aString group: nil
    ]

    lastAccessTime: aDateTime [
	"Update the last access time of the file corresponding to the receiver,
	 to be aDateTime."

	<category: 'accessing'>
	self lastAccessTime: aDateTime lastModifyTime: self lastModifyTime
    ]

    lastAccessTime: accessDateTime lastModifyTime: modifyDateTime [
	"Update the timestamps of the file corresponding to the receiver, to be
	 accessDateTime and modifyDateTime."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    lastAccessTime [
	"Answer the last access time of the file identified by the receiver"

	<category: 'accessing'>
	self subclassResponsibility
    ]

    lastChangeTime [
	"Answer the last change time of the file identified by the receiver
	 (the `last change time' has to do with permissions, ownership and the
	 like). On some operating systems, this could actually be the
	 file creation time."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    creationTime [
	"Answer the creation time of the file identified by the receiver.
	 On some operating systems, this could actually be the last change time
	 (the `last change time' has to do with permissions, ownership and the
	 like)."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    lastModifyTime: aDateTime [
	"Update the last modification timestamp of the file corresponding to the
	 receiver, to be aDateTime."

	<category: 'accessing'>
	self lastAccessTime: self lastAccessTime lastModifyTime: aDateTime
    ]

    lastModifyTime [
	"Answer the last modify time of the file identified by the receiver
	 (the `last modify time' has to do with the actual file contents)."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    refresh [
	"Refresh the statistics for the receiver"

	<category: 'accessing'>
    ]

    exists [
	"Answer whether a file with the name contained in the receiver does exist."

	<category: 'testing'>
	self subclassResponsibility
    ]

    isSymbolicLink [
	"Answer whether a file with the name contained in the receiver does exist
	 and identifies a symbolic link."

	<category: 'testing'>
	self subclassResponsibility
    ]

    isDirectory [
	"Answer whether a file with the name contained in the receiver does exist
	 and identifies a directory."

	<category: 'testing'>
	self subclassResponsibility
    ]

    isFile [
	"Answer whether a file with the name contained in the receiver does exist
	 and does not identify a directory."

	<category: 'testing'>
	^self exists and: [ self isDirectory not ]
    ]

    isRelative [
	"Answer whether the receiver identifies a relative path."

	<category: 'testing'>
	^self isAbsolute not
    ]

    isAbsolute [
	"Answer whether the receiver identifies an absolute path."

	<category: 'testing'>
	self subclassResponsibility
    ]

    isReadable [
	"Answer whether a file with the name contained in the receiver does exist
	 and is readable"

	<category: 'testing'>
	self subclassResponsibility
    ]

    isWriteable [
	"Answer whether a file with the name contained in the receiver does exist
	 and is writeable"

	<category: 'testing'>
	self subclassResponsibility
    ]

    isExecutable [
	"Answer whether a file with the name contained in the receiver does exist
	 and is executable"

	<category: 'testing'>
	self subclassResponsibility
    ]

    isAccessible [
	"Answer whether a directory with the name contained in the receiver does
	 exist and can be accessed"

	<category: 'testing'>
	self subclassResponsibility
    ]

    isFileSystemPath [
	"Answer whether the receiver corresponds to a real filesystem path."

	<category: 'testing'>
	^false
    ]

    extension [
	"Answer the extension of the receiver"

	<category: 'file name management'>
	^File extensionFor: self name
    ]

    stripExtension [
	"Answer the path (if any) and file name of the receiver"

	<category: 'file name management'>
	^File stripExtensionFrom: self name
    ]

    stripPath [
	"Answer the file name and extension (if any) of the receiver"

	<category: 'file name management'>
	^File stripPathFrom: self name
    ]

    directory [
	"Answer the Directory object for the receiver's path"

	<category: 'file name management'>
	^self parent
    ]

    parent [
	"Answer the Directory object for the receiver's path"

	<category: 'file name management'>
	^self class path: (File pathFor: self name ifNone: [ '.' ])
    ]

    fullName [
	"Answer a String with the full path to the receiver (same as #name;
	 it is useless to override this method)."

	<category: 'file name management'>
	^self name
    ]

    name [
	"Answer String with the full path to the receiver (same as #fullName)."

	<category: 'file name management'>
	self subclassResponsibility
    ]

    path [
	"Answer the path (if any) of the receiver"

	<category: 'file name management'>
	^File pathFor: self name
    ]

    stripFileName [
	"Answer the path of the receiver, always including a directory
	 name (possibly `.') and the final directory separator"

	<category: 'file name management'>
	^File stripFileNameFor: self name
    ]

    full [
	"Answer the full name of the receiver, resolving the `.' and
	 `..' directory entries, and answer the result.  Answer nil if the
	 name is invalid (such as '/usr/../../badname')"

	<category: 'file name management'>
	self subclassResponsibility
    ]

    contents [
	"Open a read-only FileStream on the receiver, read its contents,
	 close the stream and answer the contents"

	<category: 'file operations'>
	| stream contents |
	stream := self readStream.
	contents := stream contents.
	stream close.
	^contents
    ]

    touch [
	"Update the timestamp of the file corresponding to the receiver."

	<category: 'file operations'>
	| now |
	self exists 
	    ifTrue: 
		[now := DateTime now.
		self lastAccessTime: now lastModifyTime: now]
	    ifFalse: [(self open: FileStream append) close]
    ]

    open: mode [
	"Open the receiver in the given mode (as answered by FileStream's
	 class constant methods)"

	<category: 'file operations'>
	^self open: mode
	    ifFail: [SystemExceptions.FileError signal: 'could not open ' , self name]
    ]

    openDescriptor: mode [
	"Open the receiver in the given mode (as answered by FileStream's
	 class constant methods)"

	<category: 'file operations'>
	^self openDescriptor: mode
	    ifFail: [SystemExceptions.FileError signal: 'could not open ' , self name]
    ]

    open: mode ifFail: aBlock [
	"Open the receiver in the given mode (as answered by FileStream's
	 class constant methods). Upon failure, evaluate aBlock."

	<category: 'file operations'>
    	^self open: FileStream mode: mode ifFail: aBlock
    ]

    openDescriptor: mode ifFail: aBlock [
	"Open the receiver in the given mode (as answered by FileStream's
	 class constant methods). Upon failure, evaluate aBlock."

	<category: 'file operations'>
    	^self open: FileDescriptor mode: mode ifFail: aBlock
    ]

    open: class mode: mode ifFail: aBlock [
	"Open the receiver in the given mode (as answered by FileStream's
	 class constant methods)"

	<category: 'file operations'>
	self subclassResponsibility
    ]

    withReadStreamDo: aBlock [
	"Answer the result of invoking aBlock with a reading stream
	 open on me, closing it when the dynamic extent of aBlock ends."
	<category: 'file operations'>
	| stream |
	stream := self readStream.
	^[aBlock value: stream] ensure: [stream close]
    ]

    fileIn [
	"File in the receiver"

	<category: 'file operations'>
	self withReadStreamDo: [ :fs | fs fileIn ]
    ]

    readStream [
	"Open a read-only FileStream on the receiver"

	<category: 'file operations'>
	^self open: FileStream read
    ]

    withWriteStreamDo: aBlock [
	"Answer the result of invoking aBlock with a writing stream
	 open on me, closing it when the dynamic extent of aBlock ends."
	<category: 'file operations'>
	| stream |
	stream := self writeStream.
	^[aBlock value: stream] ensure: [stream close]
    ]

    writeStream [
	"Open a write-only FileStream on the receiver"

	<category: 'file operations'>
	^self open: FileStream write
    ]

    symlinkAs: destName [
	"Create destName as a symbolic link of the receiver.  The appropriate
	 relative path is computed automatically."

	<category: 'file operations'>
	self subclassResponsibility
    ]

    pathFrom: dirName [
	"Compute the relative path from the directory dirName to the receiver"

	<category: 'file operations'>
	self subclassResponsibility
    ]

    symlinkFrom: srcName [
	"Create the receiver as a symbolic link from srcName (relative to the
	 path of the receiver)."

	<category: 'file operations'>
	self subclassResponsibility
    ]

    remove [
	"Remove the file identified by the receiver"

	<category: 'file operations'>
	self subclassResponsibility
    ]

    renameTo: newName [
	"Rename the file identified by the receiver to newName"

	<category: 'file operations'>
	self subclassResponsibility
    ]

    pathTo: destName [
	"Compute the relative path from the receiver to destName."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    / aName [
	"Answer a File or Directory object as appropriate for a file named
	 'aName' in the directory represented by the receiver."

	^self at: aName
    ]

    at: aName [
	"Answer a File or Directory object as appropriate for a file named
	 'aName' in the directory represented by the receiver."

	<category: 'accessing'>
	self subclassResponsibility
    ]

    includes: aName [
        "Answer whether a file named `aName' exists in the directory represented
         by the receiver."

        <category: 'accessing'>
        ^(self at: aName) exists
    ]

    all [
	"Return a decorator of the receiver that will provide recursive
	 descent into directories for iteration methods.  Furthermore,
	 iteration on the returned wrapper will not include '.' or '..'
	 directory entries, and will include the receiver (directly, not
	 via '.')."

	<category: 'decoration'>
	^Kernel.RecursiveFileWrapper on: self
    ]

    allFilesMatching: aPattern do: aBlock [
	"Evaluate aBlock on the File objects that match aPattern (according to
	 String>>#match:) in the directory named by the receiver. Recursively
	 descend into directories."

	<category: 'enumerating'>
	self all filesMatching: aPattern do: aBlock
    ]

    createDirectory [
	"Create the receiver as a directory, together with all its parents."

	<category: 'directory operations'>
	self subclassResponsibility
    ]

    createDirectories [
	"Create the receiver as a directory, together with all its parents."

	<category: 'directory operations'>
	| parent |
	parent := self parent.
	parent exists
	    ifTrue: [
		self exists ifTrue: [
		    self isDirectory ifFalse: [ self createDirectory ].
		    ^self ] ]
	    ifFalse: [ parent createDirectories ].
	self createDirectory
    ]

    files [
	"Answer an Array with File objects for the contents of the directory
	 represented by the receiver."

	<category: 'enumerating'>
	^self reject: [ :each | each isDirectory ]
    ]

    directories [
	"Answer an Array with Directory objects for the subdirectories
	 of the directory represented by the receiver."

	<category: 'enumerating'>
	^self select: [ :each | each isDirectory ]
    ]

    entries [
	"Answer an Array with File or Directory objects for the contents
	 of the directory represented by the receiver."

	<category: 'enumerating'>
	| ws |
	ws := WriteStream on: (Array new: 50).
	self do: [:each | ws nextPut: each].
	^ws contents
    ]

    entryNames [
	"Answer an Array with the names of the files in the directory
	 represented by the receiver."

	<category: 'enumerating'>
	| ws |
	ws := WriteStream on: (Array new: 50).
	self namesDo: [:each | ws nextPut: each].
	^ws contents
    ]

    do: aBlock [
	"Evaluate aBlock once for each file in the directory represented by the
	 receiver, passing a FilePath object (or a subclass) to it.  It depends
	 on the subclass whether iteration will include the '.' and '..'
	 directory entries."

	<category: 'enumerating'>
	self namesDo: [ :name |
	    aBlock value: (self at: name) ]
    ]

    namesDo: aBlock [
	"Evaluate aBlock once for each file in the directory represented by the
	 receiver, passing its name.  It depends on the subclass whether
	 iteration will include the '.' and '..'  directory entries."

	<category: 'enumerating'>
	self subclassResponsibility
    ]

    filesMatching: aPattern [
	"Evaluate aBlock once for each file in the directory represented by the
	 receiver, passing a File or Directory object to aBlock. Returns the
	 *names* of the files for which aBlock returns true."

	<category: 'enumerating'>
	| ws |
	ws := WriteStream on: (Array new: 50).
	self namesDo: [ :name |
	    (aPattern match: name) ifTrue: [ ws nextPut: (self at: name) ] ].
	^ws contents
    ]

    reject: aBlock [
	"Evaluate aBlock once for each file in the directory represented by the
	 receiver, passing a File or Directory object to aBlock. Returns the
	 *names* of the files for which aBlock returns true."

	<category: 'enumerating'>
	| ws |
	ws := WriteStream on: (Array new: 50).
	self do: [ :each |
	    (aBlock value: each) ifFalse: [ ws nextPut: each ] ].
	^ws contents
    ]

    select: aBlock [
	"Evaluate aBlock once for each file in the directory represented by the
	 receiver, passing a File or Directory object to aBlock. Returns the
	 *names* of the files for which aBlock returns true."

	<category: 'enumerating'>
	| ws |
	ws := WriteStream on: (Array new: 50).
	self do: [ :each |
	    (aBlock value: each) ifTrue: [ ws nextPut: each ] ].
	^ws contents
    ]

    filesMatching: aPattern do: block [
	"Evaluate block on the File objects that match aPattern (according to
	 String>>#match:) in the directory named by the receiver."

	<category: 'enumerating'>
	self namesDo: [:name |
	    (aPattern match: name) ifTrue: [block value: (self at: name)]]
    ]

    nameAt: aName [
	"Answer a FilePath for a file named `aName' residing in the directory
	 represented by the receiver."

	<category: 'directory operations'>
	^File append: aName to: self asString
    ]

    namesMatching: aPattern do: block [
	"Evaluate block on the file names that match aPattern (according to
	 String>>#match:) in the directory named by the receiver."

	<category: 'enumerating'>
	self namesDo: [:name |
	     (aPattern match: name) ifTrue: [block value: name]]
    ]
]