View source for LDT/Developer Area/Lua API Model 2

=Lua API Model=

The idea is to define a model of the external API of a Lua file.<br/>
This model will then be the main input of:
* documentation generator,
* auto-completion engine,
* type-checking.

The code relative to this model is based on lua and metalua, it is accessible [[LDT/MetaLua|here]].
This model is build from [[LDT/User_Area/Documentation_Language|lua documentation language]] in code comments and later from lua code analysis. (see also : [[LDT/Developer_Area/Lua_Comment_Model|Lua Comment Model]])

====File====
A Lua file declares some global variable and types.
A file returns values (this is the values you get when you require this file) 
 
 file
 .string shortdescription
 .string description
 .map(typename, typedef) types
 .map(varname,item) globalvars
 .list(returnvalues) returns

====TypeDef====
There are some primitive types like string, number, boolean, any, nil, table, function.<br/>
TypeDef allow users to define theirs own custom types.<br/>
There are 2 kinds of typedef.

 typeDef = recordTypeDef | functionTypeDef
 
A recordTypeDef can be used to define a record (a tuple), a module or an object. (It may be a sub-type of table)

 recordTypeDef
 .string name
 .string shortdescription
 .string description
 .map(fieldname,item) fields
 
A functionTypeDef allows to define a function. Most of the time, the type and the item holding it are merged.
It may be useful to name the type of function (for iterator perhaps)

 functionTypeDef
 .string name
 .string shortdescription
 .string description
 .list(parameter) params
 .list(returnvalues) returns

====Parameter====

 parameter
 .string name 
 .typeref type
 .string description
 (.boolean optional)
 (.boolean hidden)

'''Remarks''': Hidden could be use when there is a parameter we don't want to expose in the API<br/>
'''Remarks''': hidden and optional does not need to be in the 1st version.

====Item====

 item
 .string name
 .string shortdescription
 .string description
 .typeref type


====TypeRef====
It's a reference to a type. There are 3 kinds of reference.

 typeref: externaltyperef | internaltyperef |primitivetyperef
 
 externaltyperef
 .string modulename
 .string typename
 
 internaltyperef
 .string typename
 
 primitivetyperef
 .string typename

====Return values====
A return value has references to a type defined in the Lua file.
A return value is a list of possible values to return.

e.g. if a function returns a number, or nil and err.
your function will have 2 return values :
* <code>number</code> a result
* <code>nil, err</code> if an error occured

 return
 .list(typeref) types
 .string description
 (.defaultuse)

'''Remarks''': Perhaps we could have a defaultuse entry to define the return value the type checker should use. At the moment, the first entry in types list is used to type the return value.