NaviServer - programmable web server
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ns_parseargs(n) 5.0.0a naviserver "NaviServer Built-in Commands"

Name

ns_parseargs - Parse list of arguments

Table Of Contents

Synopsis

Description

This function parses a list of arguments against an argument specification and stores the resulting bindings in local Tcl variables.

COMMANDS

ns_parseargs argspec arguments

argspec argument specifications, which is a list of specifications for single positional or non-positional arguments. When an argument spec starts with a "-", it specifies a non-positional argument. When an argument spec consists of two values, the latter one is a default. The special argument spec "--" (two dashes) denotes a potential end of the block of non-positional arguments

arguments List of arguments to be parsed

EXAMPLES

The first example shows the practical usage of ns_parseargs in a proc. The intention is to define a proc "ns_getcontent" which might be called with the optional arguments -as_file or -binary. The default value for both of these arguments is true. To achieve this, the proc "ns_getcontent" is defined with the argument spec args, which allows all kinds of arguments to be passed. As a fist call, it invokes the argument parser with the detailed argument spec. In case, the arguments can't be parsed according to the spec, "ns_parseargs" raises an error.

 #
 # Define a function with two positional arguments
 #
 proc ns_getcontent {args} {
   ns_parseargs {
       {-as_file true}
       {-binary true}
   } $args
 
   if {![string is boolean -strict $as_file]} {
     return -code error "value of '$as_file' is not boolean"
   }
   if {![string is boolean -strict $binary]} {
     return -code error "value of '$binary' is not boolean"
   }
   # ...
 }

The second example demonstrates non-positional and positional arguments with and without defaults.

 % ns_parseargs {-a {-b 1} -- c {d x}} {-- 1 }
 % lappend _ [info exists a] [info exists b] [info exists c] [info exists d]
 0 1 1 1

See Also

nsd

Keywords

NaviServer, global built-in