the big rename

[xonotic/xonotic.wiki.git] / NewQC.md

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+New QC Syntax
+=============
+
+It is possible that at some point we decide to switch QC-compiler which requires some changes to the code.
+
+~~For more information see http://dev.xonotic.org/projects/bocc~~
+
+(Update: Blub's bocc compiler didn't make it, but someone else came along, both devs [joined forces](https://github.com/graphitemaster/gmqcc/graphs/contributors) and brought us [GMQCC](https://graphitemaster.github.io/gmqcc/doc.html).
+ This is now the QuakeC compiler used by the Xonotic project.)
+
+Clean syntax:
+-------------
+
+In fteqcc there are some ambiguities regarding fieldpointers, function pointers, and field-return-types etc.
+A clean syntax is needed, the current implementation uses the following:
+
+|definition|meaning|
+|----------|-------|
+|`float foo`|global variable|
+|`float .foo`|entity field|
+|`.float foo`|fieldpointer|
+|`.float .foo`|entity field of type fieldpointer|
+|`float foo(void)`|function|
+|`float foo*(void)`|function pointer|
+|`.float foo(void)`|function returning a fieldpointer .float|
+|`.float foo*(void)`|function pointer, returning a fieldpointer .float|
+|`float .foo(void)`|entity field of type function returning float|
+|`.float .foo(void)`|entity field of type function returning fieldpointer|
+
+Function definitions:
+---------------------
+
+The old-style QC way of defining functions will not be supported, so
+
+    void(float x) something = { ... }
+
+becomes
+
+    void something(float x) { ... }
+
+which is the most common way to define functions in the xonotic code already anyway.
+
+Constants:
+----------
+
+From now on, the code
+
+    float x = 3
+
+does what the first instinct tells you: it creates a global with the initial value 3. Contrary to old QC, where it created a constant.
+To create a constant use:
+
+    const float x = 3
+
+Extendable functions:
+---------------------
+
+Since menuQC has some funny macro: ACCUMULATE\_FUNCTIONS, it seemed like a nice syntactical sugar to allow the following:
+
+    float myfunc() extendable
+    {
+        float mylocal = 3;
+    }
+
+    /* other code */
+
+    float myfunc()
+    {
+        mylocal += 5;
+        if (mylocal > 20)
+            return mylocal;
+    }
+
+    /* optionally: */
+    float myfunc() final
+    {
+        return 3;
+    }
+
+Variadic parameters (do not use yet)
+------------------------------------
+
+(This might get changed to be more flexible so do not rely on this syntax…)
+
+Another “enhancement” is the possibility to have functions with variadic parameter lists. However, the only way to sanely access them (until pointers are allowed) is via a recursive way.
+Here’s an example that assumes float parameters and prints them one after the other:
+
+    void printfloats(float count, float first, ...)
+    {
+        if (count <= 0) // if there are no parameters, return
+            return;
+        if (count == 1) { // If there's one parameter, print it, plus a new-line
+            print(strcat(ftos(first), "\n"));
+            return;
+        }
+        // Otherwise we have multiple parameters left, so print the float, and add a comma
+        print(strcat(ftos(first), ", "));
+        myprint(count-1, ...);
+    }
+
+So `myprint(4, 1, 2, 3, 4)` would print "1, 2, 3, 4\\n"
+