Tk getOpenFile

NAME

SYNOPSIS

The procedures tk_getOpenFile and tk_getSaveFile pop up a dialog box for the user to select a file to open or save. The tk_getOpenFile command is usually associated with the Open command in the File menu. Its purpose is for the user to select an existing file only. If the user enters an nonexistent file, the dialog box gives the user an error prompt and requires the user to give an alternative selection. If an application allows the user to create new files, it should do so by providing a separate New menu command.

The tk_getSaveFile command is usually associated with the Save as command in the File menu. If the user enters a file that already exists, the dialog box prompts the user for confirmation whether the existing file should be overwritten or not.

The following option-value pairs are possible as command line arguments to these two commands:

-defaultextension extension
Specifies a string that will be appended to the filename if the user enters a filename without an extension. The defaut value is the empty string, which means no extension will be appended to the filename in any case. This option is ignored on the Macintosh platform, which does not require extensions to filenames.

-filetypes filePatternList
If a File types listbox exists in the file dialog on the particular platform, this option gives the filetypes in this listbox. When the user choose a filetype in the listbox, only the files of that type are listed. If this option is unspecified, or if it is set to the empty list, or if the File types listbox is not supported by the particular platform then all files are listed regardless of their types. See the section SPECIFYING FILE PATTERNS below for a discussion on the contents of filePatternList.

-initialdir directory
Specifies that the files in directory should be displayed when the dialog pops up. If this parameter is not specified, then the files in the current working directory are displayed. This option may not always work on the Macintosh. This is not a bug. Rather, the General Controls control panel on the Mac allows the end user to override the application default directory.

-initialfile filename
Specifies a filename to be displayed in the dialog when it pops up. This option is ignored by the tk_getOpenFile command.

-parent window
Makes window the logical parent of the file dialog. The file dialog is displayed on top of its parent window.

-title titleString
Specifies a string to display as the title of the dialog box. If this option is not specified, then a default title is displayed. This option is ignored on the Macintosh platform.

If the user selects a file, both tk_getOpenFile and tk_getSaveFile return the full pathname of this file. If the user cancels the operation, both commands return the empty string.

SPECIFYING FILE PATTERNS

The filePatternList value given by the -filetypes option is a list of file patterns. Each file pattern is a list of the form typeName {extension ?extension ...?} ?{macType ?macType ...?}? typeName is the name of the file type described by this file pattern and is the text string that appears in the File types listbox. extension is a file extension for this file pattern. macType is a four-character Macintosh file type. The list of macTypes is optional and may be omitted for applications that do not need to execute on the Macintosh platform.

Several file patterns may have the same typeName, in which case they refer to the same file type and share the same entry in the listbox. When the user selects an entry in the listbox, all the files that match at least one of the file patterns corresponding to that entry are listed. Usually, each file pattern corresponds to a distinct type of file. The use of more than one file patterns for one type of file is necessary on the Macintosh platform only.

On the Macintosh platform, a file matches a file pattern if its name matches at least one of the extension(s) AND it belongs to at least one of the macType(s) of the file pattern. For example, the C Source Files file pattern in the sample code matches with files that have a .c extension AND belong to the macType TEXT. To use the OR rule instead, you can use two file patterns, one with the extensions only and the other with the macType only. The GIF Files file type in the sample code matches files that EITHER have a .gif extension OR belong to the macType GIFF.

On the Unix and Windows platforms, a file matches a file pattern if its name matches at at least one of the extension(s) of the file pattern. The macTypes are ignored.

SPECIFYING EXTENSIONS

On the Unix and Macintosh platforms, extensions are matched using globstyle pattern matching. On the Windows platforms, extensions are matched by the underlying operating system. The types of possible extensions are: (1) the special extension * matches any file; (2) the special extension "" matches any files that do not have an extension (i.e., the filename contains no full stop character); (3) any character string that does not contain any wild card characters (* and ?).

Due to the different pattern matching rules on the various platforms, to ensure portability, wild card characters are not allowed in the extensions, except as in the special extension *. Extensions without a full stop character (e.g, ~) are allowed but may not work on all platforms.

EXAMPLE

{{Text Files}

{.txt} } {{TCL Scripts} {.tcl} } {{C Source Files} {.c} TEXT}

{{GIF Files}

{.gif} }

{{GIF Files}

{} GIFF} {{All Files} * } } set filename [tk_getOpenFile -filetypes $types]

KEYWORDS

• NAME
• SYNOPSIS
• DESCRIPTION
• SPECIFYING FILE PATTERNS
• SPECIFYING EXTENSIONS
• EXAMPLE
• KEYWORDS