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<span id="Parsing-Arguments"></span><div class="header">
<p>
Previous: <a href="Validating-the-type-of-Arguments.html" accesskey="p" rel="prev">Validating the type of Arguments</a>, Up: <a href="Validating-Arguments.html" accesskey="u" rel="up">Validating Arguments</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<span id="Parsing-Arguments-1"></span><h4 class="subsection">11.9.3 Parsing Arguments</h4>
<p>If none of the preceding validation functions is sufficient there is also
the class <code>inputParser</code> which can perform extremely complex input
checking for functions.
</p>
<span id="XREFinputParser"></span><dl>
<dt id="index-inputParser">: <em><var>p</var> =</em> <strong>inputParser</strong> <em>()</em></dt>
<dd><p>Create object <var>p</var> of the inputParser class.
</p>
<p>This class is designed to allow easy parsing of function arguments. The
class supports four types of arguments:
</p>
<ol>
<li> mandatory (see <code>addRequired</code>);
</li><li> optional (see <code>addOptional</code>);
</li><li> named (see <code>addParameter</code>);
</li><li> switch (see <code>addSwitch</code>).
</li></ol>
<p>After defining the function API with these methods, the supplied arguments
can be parsed with the <code>parse</code> method and the parsing results
accessed with the <code>Results</code> accessor.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eParameters">: <em></em> <strong>inputParser.Parameters</strong></dt>
<dd><p>Return list of parameter names already defined.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eResults">: <em></em> <strong>inputParser.Results</strong></dt>
<dd><p>Return structure with argument names as fieldnames and corresponding values.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eUnmatched">: <em></em> <strong>inputParser.Unmatched</strong></dt>
<dd><p>Return structure similar to <code>Results</code>, but for unmatched parameters.
See the <code>KeepUnmatched</code> property.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eUsingDefaults">: <em></em> <strong>inputParser.UsingDefaults</strong></dt>
<dd><p>Return cell array with the names of arguments that are using default values.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eCaseSensitive">: <em></em> <strong>inputParser.CaseSensitive</strong> <em>= <var>boolean</var></em></dt>
<dd><p>Set whether matching of argument names should be case sensitive. Defaults
to false.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eFunctionName">: <em></em> <strong>inputParser.FunctionName</strong> <em>= <var>name</var></em></dt>
<dd><p>Set function name to be used in error messages; Defaults to empty string.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eKeepUnmatched">: <em></em> <strong>inputParser.KeepUnmatched</strong> <em>= <var>boolean</var></em></dt>
<dd><p>Set whether an error should be given for non-defined arguments. Defaults to
false. If set to true, the extra arguments can be accessed through
<code>Unmatched</code> after the <code>parse</code> method. Note that since
<code>Switch</code> and <code>Parameter</code> arguments can be mixed, it is
not possible to know the unmatched type. If argument is found unmatched
it is assumed to be of the <code>Parameter</code> type and it is expected to
be followed by a value.
</p>
</dd></dl>
<dl>
<dt id="index-inputParser_002eStructExpand">: <em></em> <strong>inputParser.StructExpand</strong> <em>= <var>boolean</var></em></dt>
<dd><p>Set whether a structure can be passed to the function instead of
parameter/value pairs. Defaults to true.
</p>
<p>The following example shows how to use this class:
</p>
<div class="example">
<pre class="example">function check (varargin)
p = inputParser (); # create object
p.FunctionName = "check"; # set function name
p.addRequired ("pack", @ischar); # mandatory argument
p.addOptional ("path", pwd(), @ischar); # optional argument
## create a function handle to anonymous functions for validators
val_mat = @(x) isvector (x) && all (x <= 1) && all (x >= 0);
p.addOptional ("mat", [0 0], val_mat);
## create two arguments of type "Parameter"
val_type = @(x) any (strcmp (x, {"linear", "quadratic"}));
p.addParameter ("type", "linear", val_type);
val_verb = @(x) any (strcmp (x, {"low", "medium", "high"}));
p.addParameter ("tolerance", "low", val_verb);
## create a switch type of argument
p.addSwitch ("verbose");
p.parse (varargin{:}); # Run created parser on inputs
## the rest of the function can access inputs by using p.Results.
## for example, get the tolerance input with p.Results.tolerance
endfunction
</pre></div>
<div class="example">
<pre class="example">check ("mech"); # valid, use defaults for other arguments
check (); # error, one argument is mandatory
check (1); # error, since ! ischar
check ("mech", "~/dev"); # valid, use defaults for other arguments
check ("mech", "~/dev", [0 1 0 0], "type", "linear"); # valid
## following is also valid. Note how the Switch argument type can
## be mixed into or before the Parameter argument type (but it
## must still appear after any Optional argument).
check ("mech", "~/dev", [0 1 0 0], "verbose", "tolerance", "high");
## following returns an error since not all optional arguments,
## 'path' and 'mat', were given before the named argument 'type'.
check ("mech", "~/dev", "type", "linear");
</pre></div>
<p><em>Note 1</em>: A function can have any mixture of the four API types but
they must appear in a specific order. <code>Required</code> arguments must be
first and can be followed by any <code>Optional</code> arguments. Only
the <code>Parameter</code> and <code>Switch</code> arguments may be mixed
together and they must appear at the end.
</p>
<p><em>Note 2</em>: If both <code>Optional</code> and <code>Parameter</code> arguments
are mixed in a function API then once a string Optional argument fails to
validate it will be considered the end of the <code>Optional</code>
arguments. The remaining arguments will be compared against any
<code>Parameter</code> or <code>Switch</code> arguments.
</p>
<p><strong>See also:</strong> <a href="Defining-Functions.html#XREFnargin">nargin</a>, <a href="Validating-the-type-of-Arguments.html#XREFvalidateattributes">validateattributes</a>, <a href="Validating-the-type-of-Arguments.html#XREFvalidatestring">validatestring</a>, <a href="Variable_002dlength-Argument-Lists.html#XREFvarargin">varargin</a>.
</p></dd></dl>
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Previous: <a href="Validating-the-type-of-Arguments.html" accesskey="p" rel="prev">Validating the type of Arguments</a>, Up: <a href="Validating-Arguments.html" accesskey="u" rel="up">Validating Arguments</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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