TemplateData doesn't let you have conditional meanings of parameters based on other parameters
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Description

Templates behave differently depending on whether positional parameters are explicitly declared or not. For example, for [[Template:User]] on the English Wikipedia, {{user|1=foo=bar}} will return user links for the user "foo=bar", but {{user|foo=bar}} will generate an error, as there is no "foo" parameter. However, there does not seem to be any way of distinguishing explicit positional parameters from implicit positional parameters using TemplateData. I am guessing that this ability will be needed for the Visual Editor to properly handle existing templates - see also bug 49739.


Version: unspecified
Severity: enhancement

bzimport added a project: TemplateData.Via ConduitNov 22 2014, 2:01 AM
bzimport added a subscriber: wikibugs-l.
bzimport set Reference to bz49743.
MrStradivarius created this task.Via LegacyJun 18 2013, 10:44 AM
Jdforrester-WMF added a comment.Via ConduitJul 9 2013, 8:55 PM

I'm sorry, I've read this a dozen times and I still don't understand what you think we should change. Could you re-state?

Jdforrester-WMF added a comment.Via ConduitJul 12 2013, 4:31 PM

Closing for now; please re-open if you can help us identify the issue here.

SalixAlba added a comment.Via ConduitJul 13 2013, 10:23 AM

Here is an example I'm not sure about. For {{coord}}
http://en.wikipedia.org/wiki/Template:Coord/doc
the template can have two main forms

Hours Minute Seconds {{Coord|57|18|22|N|4|27|32|W|display=inline}}

Decimal Degrees {{coord|43.6500|-79.3800|display=inline}}

In the first the Longitude degrees is the 5th parameter, in the second its the 2nd parameter. I've tried some sample template data at http://en.wikipedia.org/wiki/Template:Coord/doc#Template_Data
with documentation for Longitude degrees as the 5th parameter.

What I'm not sure about is how this will work with the second form. Will VE create {{coord|1=43.6500|5=-79.3800|display=inline}} which will badly mess up
giving an "Coordinates: Unknown argument format" error. Or will it play nice and produce {{coord|43.6500|-79.3800|display=inline}}?

Here I require the positional parameter to be silent, that is implicit, not giving the number.

There are cases where if the parameter value contains a = that you need to explicitly state the position parameter. Compare the results of {{math|foo=bar}}
with {{math|1=foo=bar}} (on en.wp). Here you need to explicitly give the parameter.

<templatedata>{
"description": "Encodes the latitude and longitude coordinates of a location, provides a link to map of the location.",
"params": {

"1": {
  "label": "Latitude degrees",
  "description": "The degrees part of the latitude. This can either be a whole number in which case minutes and seconds can also be provided in subsequent parameters, or in decimal format, negative for south eg -79.38.",
  "type": "number",
  "required": true
},
"2": {
  "label": "Latitude minutes",
  "description": "The minutes part of the latitude. Do not be overly precise, 1' is approximately 1.5km, Not used if decimal degrees are specified.",
  "type": "number",
  "required": false
},
"3": {
  "label": "Latitude seconds",
  "description": "The minutes part of the latitude. Do not be overly precise,  1\" is approximately 30m. Not used if decimal degrees are specified.",
  "type": "number",
  "required": false
},
"4": {
  "label": "Latitude direction",
  "description": "Direction part of latitude: N or S. Not used if decimal degrees are specified.",
  "type": "string",  
  "required": false
},
"5": {
  "label": "Longitude degrees",
  "description": "The degrees part of the longitude. This can either be a whole number in which case minutes and seconds can also be provided in subsequent parameters, or in decimal format, negative for west eg -79.38.",
  "type": "number",
  "required": true
},
"6": {
  "label": "Longitude minutes",
  "description": "The minutes part of the longitude. Do not be overly precise 1' is approximately 1.5km. Not used if decimal degrees are specified.",
  "type": "number",
  "required": false
},
"7": {
  "label": "Longitude seconds",
  "description": "The minutes part of the longitude. Do not be overly precise 1\" is approximately 30m. Not used if decimal degrees are specified.",
  "type": "number",
  "required": false
},
"8": {
  "label": "Longitude direction",
  "description": "Direction part of longitude: E or W. Not used if decimal degrees are specified.",
  "type": "string",  
  "required": false
},
"9": {
  "label": "Coordinate parameters",
  "description": "Optional parameters separated by an underscore '_', dim:N (viewing diameter in metres), region:R (ISO 3166-1 alpha-2 or ISO 3166-2 code), type:T (eg landmark or city(30,000)). For example 'dim:30_region:US-WI_type:event'",
  "type": "string",  
  "required": false
},
"display": {
  "label": "Display",
  "description": "Where it is displayed. Can be one of: 'inline' in the body of the article (default), 'title' at the top of the article or 'inline,title' both",
  "type": "string",  
  "required": false
},
"name": {
  "label": "Name",
  "description": "a label to place on maps (default is PAGENAME)",
  "type": "string",  
  "required": false
},
"notes": {
  "label": "Notes",
  "description": "text displayed immediately following the coordinates",
  "type": "string",  
  "required": false
},
"format": {
  "label": "Format",
  "description": "How the coordinates are displayed, either 'dec' or 'dms'",
  "type": "string",  
  "required": false
}

}}</templatedata>

Jdforrester-WMF added a comment.Via ConduitJul 15 2013, 1:34 AM

You are right, this is a mess - because this is a template that is broken by design.

The TemplateData you have written in comment 3 is wrong - most notably:

"2": {
  "label": "Latitude minutes",
  "description": "The minutes part of the latitude. Do not be overly precise,

1' is approximately 1.5km, Not used if decimal degrees are specified.",

  "type": "number",
  "required": false
},

This is not true. "2" is "either Latitude minutes or Longitude decimal depending on other parameters". Both meanings of the second positional parameter can be used implicitly - hence my confusion. Have re-named to "TemplateData doesn't let you have conditional meanings of parameters based on other parameters" which I think captures the issue best?

In general, this is simply an example of a ridiculously-confusing template for users. I'd very strongly recommend just fixing the template (by splitting the two users into different templates; use a single parent template to implement the proper RDFa hinting equivalently).

Otherwise, I can't see what resolution you'd expect us to come up with - descriptions that change depending on the phase of the moon? TemplateData does not, and will not, contain conditionality in its definitions.

SalixAlba added a comment.Via ConduitJul 15 2013, 6:20 AM

Its a template used on 863,827 pages, so I guess people have been able to use it just fine. Its not broken by design its just a template which makes heavy use of http://en.wikipedia.org/wiki/Function_overloading which differs by the arity of its arguments, a well used software design practice. The problem is that the templatedata systems does not allow for this paradigm.

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