[MacPerl] MPEdit -- announce

[ajf@afco.demon.co.uk (Alan Fry)]

MPEdit is a small MacPerl Text Editor module, the first version of which
may be found (with many thanks to Vicki here) on:

    http://www.ptf.com/macperl/depts/Code/Tools&Misc./MPEdit_1.0.0.sea.hqx

and listed on the Code page at

    http://www.ptf.com/macperl/depts/Code/index.html

Here is a brief description of the module for those who might be thinking
about whether to download it or not. The size of the folder is about 63k --
MPEdit.pm itself is about 17k.

Essentially, the module gives MacPerl a new function MPE() for which the
argument may be either a string or a reference to a file name. In either
case, a new MPEdit window is opened with the string or contents of the file
written to it. In this sense MPE() behaves similarly to the Perl print()
function.

The MPEdit window however functions as a fully fledged (that may be going a
bit too far, but it has feathers enough at least to avoid crash landing)
Text Editor. It has its own MenuBar with "File Menu" options of Open,
Close, Save Save As and Quit plus "Edit Menu" options of Cut, Copy, Paste,
Select All, Find and Find Again. Most of the Menu Bar options have
'command-key' equivalents.

The contents of the MPEdit window (after an editing session) may be saved
to the file it came from, or saved to a new file, just as with any ordinary
text editor. In either case, or even if the contents of the window are not
saved to disk, the text is returned to the calling program and can be
retrieved by an assignment "$str = MPE()".

The MPEdit window is an ordinary MacPerl window with one significant
difference, namely that it is aware of its own existence. Hence a click in
some other window (including another MacPerl window) will send MPEdit into
the background and it will restore the Menu Bar to the original state. A
click in the MPEdit window, if it is the background, will bring it to the
front with the MenuBar changed back to display the MPEdit options. In this
sense the MPEdit window behaves almost as though it belonged to a different
application running in parallel with MacPerl.

Otherwise, the MPEdit window behaves (hopefully) exactly as a Macintosh
window should behave. It can be 'dragged', 'resized' and zoomed, and is
equipped with functional scroll bars with proper 'tracking'. The body of
text is scrolled automatically to keep either the caret or the text
selected in a 'Find' somewhere in the visible region. The text can of
course be scrolled manually but 'live scrolling' is not supported -- yet.
There will probably be some bugs to be found in some or all of these
routines. It is easier said than done.

Session options, to do with window size and position, font, font size, line
wrap and so forth, can be set by a statement at the beginning of the script
using the module, if the the default values are unacceptable. Provision of
a "preferences file" might be possible in the future.

Three questions have arisen writing this script and I wonder if anyone has
any comments on or answers to these points.

Firstly I think DisposeMenu() is broken. In 'MPEdit.pm' a work-around of
sorts stops (spectacular) crashes (in all cases I hope) but leaves a memory
leak (I think).

Secondly TECut/Copy/Paste transfers to and from _private_ scrap. IM
suggests this behaviour is correct for unstyled text and goes on to say
text can be transferred from private to desk scrap using TEToScrap(). The
question is how? I cannot get it to work. Has anyone any experience in this
area? It matters IMHO, since if there is no private scrap TEPaste() will
take text from the desk scrap. The results of a 'Paste' can therefore
sometimes be unexpected.

Thirdly TEGetText() seems to be partly broken in so far as the handle
points to garbage if there is no text in the field. A work-around is to
look at 'teLength' and avoid the handle if 'teLength' is zero. Is it a bug,
or is it expected behaviour?

May I add two tributes. The first is to Matthias for the inticate and
elegant structure of hooks and panes through which events weave their way
through all the Toolbox modules. It is remarkable fact that despite its
comprehensiveness, the design is such that if there is need to alter a
corner of it for some particular purpose, it is possible to do so. The
structure is not so to speak immutably set in concrete despite being
complete in itself. It is a wonderfully flexible toolbox.

The second tribute is to Vicki and Chris for MPPE which proves such an
invaluable companion. Whatever it is you have forgotten, it is to be found
therein (usually pretty easily), and whatever the problem it kicks you off
succinctly in the right direction.

So that's it. MPEdit attempts a TextEditor with a pipeline to and from
MacPerl. Suggestions, comments, and criticism would be most welcome.

Have fun with it!

Alan Fry



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