param_info ( : : ProcName, ParamName, Slot : Information )

Information concerning the procedure parameters.

The operator param_info is used for calling up the online-texts assigned to a parameter of an indicated procedure. The form of information available for each parameter (Slot), can be called up by using the operator query_param_info. At the moment the following slots are available:

  'description'
              Description of the parameter.

  'description.latex'      
              Description of the parameter in LaTeX notation.

  'parameter_class'  
              Parameter classes: 'input_object', 'output_object', 
              'input_control' or 'output_control'.

  'type_list'   
              Permitted type(s) of data for parameter values 
              (for control parameters only).
	          Values: 'real', 'integer' or 'string'.

  'sem_type'
		Semantic type of the parameter. This is important to allow the 
		assignment of the parameters to object classes in object-oriented
		languages (C++, Smalltalk). If more than one parameter belongs
		semantically to one type, this fact is indicated as well. So far 
		the following objects are supported:
			object, image, region, xld, 		
			xld_cont, xld_para, xld_poly, xld_ext_para, xld_mod_para,
		 	integer, real, number, string,
			channel, greyval, window.id,
			histogram, distribution,
			point(.x, .y), extent(.x, .y),
			angle(.rad oder .deg),
			circle(.center.x, .center.y, .radius),
			arc(.center.x, .center.y, .angle.rad, .begin.x, .begin.y),
			ellipse(.center.x, .center.y, .angle.rad, .radius1, .radius2),
			line(.begin.x, .begin.y, .end.x, .end.y)
			rectangle(.origin.x, .origin.y, .corner.x, .corner.y
					 	   bzw. .extent.x, .extent.y),
			polygon(.x, .y), contour(.x, .y),
			coordinates(.x, .y), chord(.x1, .x2, .y),
			chain(.begin.x, .begin.y, .code),

  'default_type'   
              Default-type for parameter values (for control parameters only).
		This type of parameter is the one HORUS/C uses in the
		"simple mode". If 'none' is indicated, the "tuplet mode" must
		be used. 
		Values: 'real', 'integer', 'string' or 'none'.

  'default_value'
	      Default-value for the parameter
		(for input-control parameters only).
		It is the question of mere information only (the parameter
		value must be transmitted explicitly, even if the 
		default-value is used). This entry serves only as a notice, a
		point of departure for own experiments. The values have been
		selected so that they normally do not cause any errors but
		generate something that makes sense.

  'multivalue'  
	      'true', if more than one value is permitted in this parameter position,
		otherwise 'false'. 

  'multichannel'  
	      'true', in case the input image object may have more than one channel.

  'mixed_type'
	      For control parameters exclusively and only if value tuplets
		('multivalue'-'true') and various types of data are permitted
		for the parameter values ('type_list' having more than one value).
		In this case Slot indicates, whether it is allowable to have values
		of different types in one tuplet ('true' or 'false').	

  'values'
		Selection of possible values.

  'value_list'
	      In case a parameter can only take a limited number of values, these
		will be indicated explicitly.

  'valuemin'
		Minimum value of a value interval.

  'valuemax'
		Maximum value of a value interval.

  'valuefunction'
		Function discribing the course of the values for a series of tests
          (lin, log, quadr, ...).

  'steprec'
		Recommended step width of the parameter values in a series of tests.

  'stepmin'
		Minimum step width of the parameter values in a series of tests.

  'valuenumber'
              Expression describing the number of parameters as such or in relation
		to other parameters.

  'assertion' 
              Expression describing the parameter values as such or in relation to other
		parameters.


The online-texts will be taken from the files english.hlp, english.sta, english.key, english.num and english.idx which will be searched by HORUS in the currently used directory or the directory 'help_dir' (see also get_system and set_system).


Parameters

ProcName (input_control)
string -> string
Name of the procedure on whose parameter more information is needed.
Default value: 'param_info'

ParamName (input_control)
string -> string
Name of the parameter on which more information is needed.
Default value: 'Slot'

Slot (input_control)
string -> string
Desired information.
Default value: 'description'
List of values: 'description', 'type_list', 'default_type', 'sem_type', 'default_value', 'values', 'value_list', 'valuemin', 'valuemax', 'valuefunction', 'valuenumber', 'assertion', 'steprec', 'stepmin', 'mixed_type', 'multivalue', 'multichannel'

Information (output_control)
string-array -> string
Information (empty in case there is no information available).


Result

The operator param_info returns the value TRUE if the parameters are correct and the helpfiles are available. Otherwise an exception is raised.


Possible Predecessors

search_keyword, search_proc


Alternatives

proc_info1, proc_info2, proc_info3


See also

query_param_info, proc_info, proc_name



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