[naviserver-tracker] [ naviserver-Feature Requests-1122940 ] Tcl command switch parsing routines

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Feature Requests item #1122940, was opened at 2005-02-15 01:05
Message generated for change (Comment added) made by sdeasey
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https://sourceforge.net/tracker/?func=detail&atid=719009&aid=1122940&group_id=130646

Category: C-API
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Stephen Deasey (sdeasey)
Assigned to: Stephen Deasey (sdeasey)
Summary: Tcl command switch parsing routines

Initial Comment:

Parsing the switches and arguments for a Tcl command
can be a real pain: it's very easy to make off-by-one
errors, and it often involves a lot of repetitive
typing which obscures the real intent of the command.

The attached patch provides the routine Ns_ParseObjv. 
It parses switches and arguments, checks types, and
generates error/usage messages automatically.  Switches
are handled efficiently via indexed lookups.

The intent is not only to reduce the number of errors
in switch handling code but to make switch handling
such an easy task that developers are more likely to
design easy to use, tcl-friendly APIs rather than APIs
that are convenient to implement.




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>Comment By: Stephen Deasey (sdeasey)
Date: 2005-02-15 01:07

Message:
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Here's an example:

int
NsTclCacheCreateObjCmd(ClientData arg, Tcl_Interp *interp,
int objc, Tcl_Obj *CONST objv[])
{
    Ns_Cache       *cache;
    Ns_DString      ds;
    int             scope = CACHE_SERVER;
    int             size  = 0, objsize = 0, entries = 0,
timeout = 0;
    char           *name  = NULL;

    Ns_ObjvTable scopes[] = {
        {"global", CACHE_GLOBAL},
        {"server", CACHE_SERVER},
        {"interp", CACHE_INTERP},
        NULL,      NULL
    };
    Ns_ObjvSpec opts[] = {
        {"-scope",   Ns_ObjvIndex,  &scope,   &scopes},
        {"-size",    Ns_ObjvInt,    &size,    NULL},
        {"-objsize", Ns_ObjvInt,    &objsize, NULL},
        {"-entries", Ns_ObjvInt,    &entries, NULL},
        {"-timeout", Ns_ObjvInt,    &timeout, NULL},
        {"--",       Ns_ObjvBreak,  NULL,     NULL},
        {NULL, NULL, NULL, NULL}
    };
    Ns_ObjvSpec args[] = {
        {"cache",    Ns_ObjvString, &name, NULL},
        {NULL, NULL, NULL, NULL}
    };
    if (Ns_ParseObjv(opts, args, interp, 1, objc, objv) !=
NS_OK) {
        return TCL_ERROR;
    }

    /* . . . */

    return TCL_OK;
}



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