Tk_GetUid, Tk_Uid — convert from string to unique identifier
Tk_GetUid returns the unique identifier corresponding
Unique identifiers are similar to atoms in Lisp, and are used
in Tk to speed up comparisons and
searches. A unique identifier (type Tk_Uid) is a string pointer
and may be used anywhere that a variable of type
could be used. However, there is guaranteed to be exactly
one unique identifier for any given string value. If Tk_GetUid
is called twice, once with string a and once with string
b, and if a and b have the same string value
(strcmp(a, b) == 0), then Tk_GetUid will return exactly
the same Tk_Uid value for each call (Tk_GetUid(a) == Tk_GetUid(b)).
This means that variables of type
Tk_Uid may be compared directly (x == y) without having to call
In addition, the return value from Tk_GetUid will have the
same string value as its argument (strcmp(Tk_GetUid(a), a) == 0).
atom, unique identifier
- char *string (in)
String for which the corresponding unique identifier is
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