[fpc-pascal] Next language feature for pas2js...

[Ryan Joseph]

> On May 1, 2018, at 3:17 PM, Michael Van Canneyt <michael at freepascal.org> wrote:
> 
>> So constants must be part of the class? In the example below gl.COLOR_BUFFER_BIT is scoped to WebGLRenderingContext so I guess that’s the reason.
> 
> Yes.
> 
> Constants without expression can only exist in an external class.

Just curious but why can’t you declare a const anywhere for any reasons?

> 
>> 
>> Also I mistyped, GLfloat is a type so how do this map to JS, or do I even need to since the names are the same?
> 
> You need to define types.
> 
> type
>  GLfloat = double;

Why do we need to redefine the type if it’s already defined in the JS library? GLfloat isn’t a double also but see my other reply.

From the link you posted there are these types. Is that even JavaScript? I don’t remember there being typedefs in it or void functions.

typedef unsigned long  GLenum;
typedef boolean        GLboolean;
typedef unsigned long  GLbitfield;
typedef byte           GLbyte;         /* 'byte' should be a signed 8 bit type. */
typedef short          GLshort;
typedef long           GLint;
typedef long           GLsizei;
typedef long long      GLintptr;
typedef long long      GLsizeiptr;
// Ideally the typedef below would use 'unsigned byte', but that doesn't currently exist in Web IDL.
typedef octet          GLubyte;        /* 'octet' should be an unsigned 8 bit type. */
typedef unsigned short GLushort;
typedef unsigned long  GLuint;
typedef unrestricted float GLfloat;
typedef unrestricted float GLclampf;

There’s other types also like dictionaries and interface. How do those work? I don’t remember those being in JS either….

dictionary WebGLContextAttributes
 {
    GLboolean alpha = true;
    GLboolean depth = true;
    GLboolean stencil = false;
    GLboolean antialias = true;
    GLboolean premultipliedAlpha = true;
    GLboolean preserveDrawingBuffer = false;
    WebGLPowerPreference powerPreference = "default";
    GLboolean failIfMajorPerformanceCaveat = false;
};

interface WebGLActiveInfo
 {
    readonly attribute GLint size;
    readonly attribute GLenum type;
    readonly attribute DOMString name;
};
> 
>> 
>> How does this JS translate to Pascal then? drawingBufferWidth are read only properties but no type is specified so how does Pascal handle all the untyped variables we see in JS?
> 
> This is pascal. You need a type.
> 
> https://www.khronos.org/registry/webgl/specs/latest/1.0/
> 
> shows that drawingBufferWidth has type GLsizei, which is a long.
> 
> If you don't know the type, use JSValue. It's the 'unknown type'. It has
> limited possibilities, in essence you'll need to typecast a JSValue before
> using it. You can assign JSValues of course.

I see, that reference I used wasn’t complete.



Regards,
	Ryan Joseph