Tk_GetUid, Tk_Uid - convert from string to unique identi
#typedef char *Tk_Uid
char *string (in) String for which
ing unique iden
Tk_GetUid returns the unique identifier corresponding to
string. 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 ``char *''
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
strcmp. In addition, the return value from Tk_GetUid will
have the same string value as its argument (str
cmp(Tk_GetUid(a), a) == 0).
atom, unique identifier