Interfacing Raku to Gnome GTK+

Gnome::Gio::File

File and Directory Handling

Description

Gnome::Gio::File is a high level abstraction for manipulating files on a virtual file system. N-GFiles are lightweight, immutable objects that do no I/O upon creation. It is necessary to understand that Gnome::Gio::File objects do not represent files, merely an identifier for a file.

To construct a Gnome::Gio::File, you can use:

  • .new(:path) if you have a path.

  • .new(:uri) if you have a URI.

  • .new(:commandline-arg) for a command line argument.

One way to think of a Gnome::Gio::File is as an abstraction of a pathname. For normal files the system pathname is what is stored internally, but as N-GFiles are extensible it could also be something else that corresponds to a pathname in a userspace implementation of a filesystem.

Many of the native subroutines originally in this module are not implemented in this Raku class. This is because I/O is very well supported by Raku and there is no need to provide I/O routines here. This class mainly exists to handle returned native objects from other classes. The most important calls needed are thus to get the name of a file or url.

Synopsis

Declaration

unit class Gnome::Gio::File;
also is Gnome::N::TopLevelClassSupport;

Note

Gnome::Gio::File is defined as an interface in the Gnome libraries and therefore should be defined as a Raku role. However, many Gnome modules return native Gnome::Gio::File objects as if they are class objects. There aren’t even Gnome classes using it as an interface. Presumably, it is defined like that so the developer can create classes using the File class as an interface which will not be the case in Raku.

Note

Gnome::Gio::File has many functions of which a large part will not be made available in Raku. This is because many are about read/write, move and rename which Raku is able to do very nice.

Types

class N-GFile

Native object to hold a file representation

Methods

new

:path

Create a new File object using a path to a file.

multi method new ( Str :$path! )

:uri

Create a new File object using a uri.

multi method new ( Str :$uri! )

:commandline-arg, :cwd

Creates a Gnome::Gio::File with the given argument from the command line. The value of arg can be either a URI, an absolute path or a relative path resolved relative to the current working directory. This operation never fails, but the returned object might not support any I/O operation if arg points to a malformed path.

Note that on Windows, this function expects its argument to be in UTF-8 – not the system code page. This means that you should not use this function with string from argv as it is passed to main(). g-win32-get-command-line() will return a UTF-8 version of the commandline. Gnome::Gio::Application also uses UTF-8 but g-application-command-line-create-file-for-arg() may be more useful for you there. It is also always possible to use this function with Gnome::Gio::OptionContext arguments of type G-OPTION-ARG-FILENAME.

Optionally a directory relative to the argument can be given in $cwd. Otherwise the working directory of the application is used.

multi method new ( Str :$commandline-arg!, Str :$cwd? )

:native-object

Create a File object using a native object from elsewhere. See also Gnome::N::TopLevelClassSupport.

multi method new ( N-GObject :$native-object! )

get-basename

Gets the base name (the last component of the path) for a given Gnome::Gio::File.

If called for the top level of a system (such as the filesystem root or a uri like sftp://host/) it will return a single directory separator (and on Windows, possibly a drive letter).

The base name is a byte string (not UTF-8). It has no defined encoding or rules other than it may not contain zero bytes. If you want to use filenames in a user interface you should use the display name that you can get by requesting the G-FILE-ATTRIBUTE-STANDARD-DISPLAY-NAME attribute with query-info().

This call does no blocking I/O.

Returns: (type filename) : string containing the Gnome::Gio::File’s base name, or undefined if given Gnome::Gio::File is invalid. The returned string should be freed with g-free() when no longer needed.

method get-basename ( --> Str )

get-child, get-child-rk

Gets a child of this File with basename equal to name.

Note that the file with that specific name might not exist, but you can still have a Gnome::Gio::File that points to it. You can use this for instance to create that file.

This call does no blocking I/O.

Returns: a Gnome::Gio::File to a child specified by name. Free the returned object with .clear-object().

method get-child ( Str $name --> N-GFile )
method get-child-rk ( Str $name --> Gnome::Gio::File )
  • Str $name; (type filename): string containing the child’s basename

get-child-for-display-name, get-child-for-display-name-rk

Gets the child for a given display-name (i.e. a UTF-8 version of the name). If this function fails, it returns undefined and error will be set. This is very useful when constructing a Gnome::Gio::File for a new file and the user entered the filename in the user interface, for instance when you select a directory and type a filename in the file selector.

This call does no blocking I/O.

Returns: a native File object to the specified child, or undefined if the display name couldn’t be converted.

For the -rk() version, when an error takes place, an error object is set and the returned object is invalid. The error is stored in the attribute $.last-error. Free the returned object with clear-object().

method get-child-for-display-name (
  Str $display_name --> N-GFile
)

method get-child-for-display-name-rk (
  Str $display_name --> Gnome::Gio::File
)

Example

my Gnome::Gio::File $f .= new(:path<t/data/g-resources>);
my Gnome::Gio::File $f2 = $f.get-child-for-display-name-rk('rtest')
die $f.last-error.message unless $f2.is-valid;
  • Str $display_name; string to a possible child

get-parent, get-parent-rk

Gets the parent directory for the file. If the file represents the root directory of the file system, then undefined will be returned.

This call does no blocking I/O.

Returns: a Gnome::Gio::File structure to the parent of the given Gnome::Gio::File or undefined if there is no parent. Free the returned object with clear-object().

method get-parent ( --> N-GFile )
method get-parent-rk ( --> Gnome::Gio::File )

get-parse-name

Gets the parse name of the file. A parse name is a UTF-8 string that describes the file such that one can get the Gnome::Gio::File back using parse-name().

This is generally used to show the Gnome::Gio::File as a nice full-pathname kind of string in a user interface, like in a location entry.

For local files with names that can safely be converted to UTF-8 the pathname is used, otherwise the IRI is used (a form of URI that allows UTF-8 characters unescaped).

This call does no blocking I/O.

Returns: a string containing the Gnome::Gio::File’s parse name.

method get-parse-name ( --> Str )

get-path

Gets the local pathname for Gnome::Gio::File, if one exists. If non-undefined, this is guaranteed to be an absolute, canonical path. It might contain symlinks.

This call does no blocking I/O.

Returns: (type filename) : string containing the Gnome::Gio::File’s path, or undefined if no such path exists. The returned string should be freed with g-free() when no longer needed.

method get-path ( --> Str )

get-relative-path

Gets the path for descendant relative to parent.

This call does no blocking I/O.

Returns: string with the relative path from descendant to parent, or undefined if descendant doesn’t have parent as prefix.

method get-relative-path ( N-GFile $descendant --> Str )
  • N-GFile $descendant; input Gnome::Gio::File

get-uri

Gets the URI for the file.

This call does no blocking I/O.

Returns: a string containing the Gnome::Gio::File’s URI. The returned string should be freed with g-free() when no longer needed.

method get-uri ( --> Str )

get-uri-scheme

Gets the URI scheme for a Gnome::Gio::File. RFC 3986 decodes the scheme as:

URI = scheme ":" hier-part [ "?" query ] [ "#" fragment ]

Common schemes include “file”, “http”, “ftp”, etc.

This call does no blocking I/O.

Returns: a string containing the URI scheme for the given Gnome::Gio::File. The returned string should be freed with g-free() when no longer needed.

method get-uri-scheme ( --> Str )

has-parent

Checks if file has a parent, and optionally, if it is parent.

If parent is undefined then this function returns True if file has any parent at all. If parent is non-undefined then True is only returned if file is an immediate child of parent.

Returns: True if file is an immediate child of parent (or any parent in the case that parent is undefined).

method has-parent ( N-GFile $parent --> Bool )
  • N-GFile $parent; the parent to check for, or undefined

has-prefix

Checks whether file has the prefix specified by prefix.

In other words, if the names of initial elements of file’s pathname match prefix. Only full pathname elements are matched, so a path like /foo is not considered a prefix of /foobar, only of /foo/bar.

A Gnome::Gio::File is not a prefix of itself. If you want to check for equality, use equal().

This call does no I/O, as it works purely on names. As such it can sometimes return False even if file is inside a prefix (from a filesystem point of view), because the prefix of file is an alias of prefix.

Virtual: prefix-matches

Returns: True if the files’s parent, grandparent, etc is prefix, False otherwise.

method has-prefix ( N-GFile $prefix --> Bool )
  • N-GFile $prefix; input Gnome::Gio::File

has-uri-scheme

Checks to see if a Gnome::Gio::File has a given URI scheme.

This call does no blocking I/O.

Returns: True if Gnome::Gio::File’s backend supports the given URI scheme, False if URI scheme is undefined, not supported, or Gnome::Gio::File is invalid.

method has-uri-scheme ( Str $uri_scheme --> Bool )
  • Str $uri_scheme; a string containing a URI scheme

is-native

Checks to see if a file is native to the platform.

A native file is one expressed in the platform-native filename format, e.g. “C:\Windows” or “/usr/bin/”. This does not mean the file is local, as it might be on a locally mounted remote filesystem.

On some systems non-native files may be available using the native filesystem via a userspace filesystem (FUSE), in these cases this call will return False, but get-path() will still return a native path.

This call does no blocking I/O.

Returns: True if file is native

method is-native ( --> Bool )

query-default-handler

Returns the Gnome::Gio::AppInfo that is registered as the default application to handle the file specified by file.

If cancellable is not undefined, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error G-IO-ERROR-CANCELLED will be returned.

Returns: a Gnome::Gio::AppInfo if the handle was found, undefined if there were errors and $.last-error becomes valid. When you are done with it, release it with clear-object()

method query-default-handler (
  N-GObject $cancellable --> Gnome::Gio::AppInfo
)
  • N-GObject $cancellable; optional Gnome::Gio::Cancellable object, undefined to ignore. (TODO: Cancellable not defined yet)

query-info

Gets the requested information about specified file. The result is a Gnome::Gio::FileInfo object that contains key-value attributes (such as the type or size of the file).

The attributes value is a string that specifies the file attributes that should be gathered. It is not an error if it’s not possible to read a particular requested attribute from a file - it just won’t be set. attributes should be a comma-separated list of attributes or attribute wildcards. The wildcard “” means all attributes, and a wildcard like “standard::” means all attributes in the standard namespace. An example attribute query be “standard::*,owner::user”. The standard attributes are available as defines, like Gnome::Gio::-FILE-ATTRIBUTE-STANDARD-NAME.

If cancellable is not undefined, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error G-IO-ERROR-CANCELLED will be returned.

For symlinks, normally the information about the target of the symlink is returned, rather than information about the symlink itself. However if you pass Gnome::Gio::-FILE-QUERY-INFO-NOFOLLOW-SYMLINKS in flags the information about the symlink itself will be returned. Also, for symlinks that point to non-existing files the information about the symlink itself will be returned.

If the file does not exist, the G-IO-ERROR-NOT-FOUND error will be returned. Other errors are possible too, and depend on what kind of filesystem the file is on.

Returns: a Gnome::Gio::FileInfo for the given file, or undefined on error. Free the returned object with clear-object().

method query-info ( Str $attributes, GFileQueryInfoFlags $flags, GCancellable $cancellable, N-GError $error --> GFileInfo )

  • Str $attributes; an attribute query string

  • UInt $flags; a set of GFileQueryInfoFlags

  • N-GObject $cancellable; optional Gnome::Gio::Cancellable object, undefined to ignore