W3C home > Mailing lists > Public > www-amaya-dev@w3.org > January 2000

i18n of Amaya, typing, memory leaks, etc.

From: <bglbv@my-deja.com>
Date: Sun, 9 Jan 2000 19:35:13 -0500 (EST)
Message-ID: <20000110003120.5358.qmail@my-deja.com>
To: www-amaya-dev@w3.org
I've been working on the XK_Multi_key recognition problem, thinking it would
be an easy fix. But that has been like opening Pandora's box: I keep
discovering latent bugs, type mismatches (I'm an Ada programmer at heart,
my notion of type matching is stricter than most C compilers'---but that's
what it takes to write portable, bug-free code), and so on.

1. thotlib/unicode/uconvert.c : 

Just how is one supposed to know whether the value returned by ISO2WideChar()
has been dynamically allocated by TtaAllocString() --- and should therefore
be deallocated after use, since Amaya doesn't seem to include a garbage
collector --- or simply cast from the input argument (in which case it is
out of the question to deallocate it)?

I've seen code that uses the result of ISO2WideChar() as part of a larger
expression, without capturing it in a named variable; this will have to
change if ISO2WideChar() is determined to return dynamically allocated memory.

A proper, well-designed interface specification is needed for these string
conversion routines.

Another problem I see is the lack of a counted-string version of ISO2WideChar(),
one that would take the number of characters to be converted as an additional
argument instead of relying on a final '\0'.

2. GTK+ stuff:

I've just been patching the GTK version of XCharTranslation()
(in thotlib/dialogue/interface.c). Please respect the GTK+ type system!
In particular, be careful about type casts between guint and int, gchar
and char. Don't write
   gpointer data;
   int frame;
   frame = (int) data;
but rather
   frame = GPOINTER_TO_INT (data);

GTK+ itself has a problem with internationalisation: they haven't decided
what to do. What's worse, they define their own character type gchar but
don't provide any API calls that I could find to convert between gchar
and other character types (char, wchar, etc.) To me, that's reason enough to:

(a) take one's time in converting from Motif to GTK+, since the latter
isn't i18n-ready and some of us would like to see support for Arabic and
so on; [actually I'm more interested in Cyrillic, Latin-2, Latin-3, but
I entirely sympathise with those who want to play with bidirectional text;
anyway, some of the issues are common, and might even help Chinese users]

(b) define what interface would be required. How about the following?
I'd rather not start writing too much code before the interface has been
agreed upon, so can the Amaya development team please let us know what
_they_ would be willing to adopt? Thanks.
---------
/* gconvert.h */
gchar char2gchar (const char c);	/* may be a macro */
char gchar2char (const gchar gc);	/* may be a macro */

/* The following write the result into the memory pointed to by their
   last argument, and return a pointer to that memory. They do not
   allocate any memory from the heap.
 */
gchar *str2gstr (const char *from, gchar *to);
gchar *nstr2gstr (const char *from, size_t n, gchar *to);
char *gstr2str (const gchar *from, char *to);
char *ngstr2str (const gchar *from, size_t n, char *to);

/* The following translate exactly n characters */
void nchar2gchar (size_t n, const char *from, gchar *to);
void ngchar2char (size_t n, const gchar *from, char *to);
----------
/* ugconvert.h */
CHAR_T gchar2Uchar (const gchar c);	/* may be a macro */
gchar Uchar2gchar (const UCHAR_T uc);	/* may be a macro */

STRING gstr2Ustr (const gchar *from, STRING to);
STRING ngstr2Ustr (const gchar *from, size_t n, STRING to);
gchar *Ustr2gstr (const STRING from, gchar *to);
gchar *nUstr2gstr (const STRING from, size_t n, gchar *to);

void ngchar2Uchar (size_t n, const gchar *from, STRING to);
void nUchar2gchar (size_t n, const STRING from, gchar *to);
----------
If you can come up with more readable names that still fit into some
coherent pattern, please feel free. 

Note the avoidance of dynamic memory allocation in this proposal:
the choice between malloc(), XtMalloc(), g_malloc(), TtaAllocString(),
TtaGetMemory() and who knows what else is best left to the caller.
It is my opinion that the stuff in uconvert.h should be equally
free of memory allocation side effects. That means ISO2WideChar() is bad.
Received on Monday, 10 January 2000 02:59:14 UTC

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