Merge pull request #5507 from ethereum/docs-move

Move function related content to contracts doc

docs/contracts.rst

@@ -485,6 +485,108 @@ value types and strings.
 Functions
 *********
 
+Function Parameters and Return Variables
+========================================
+
+As in JavaScript, functions may take parameters as input. Unlike in JavaScript
+and C, functions may also return an arbitrary number of values as output.
+
+Function Parameters
+-------------------
+
+Function parameters are declared the same way as variables, and the name of
+unused parameters can be omitted.
+
+For example, if you want your contract to accept one kind of external call
+with two integers, you would use something like::
+
+    pragma solidity >=0.4.16 <0.6.0;
+
+    contract Simple {
+        uint sum;
+        function taker(uint _a, uint _b) public {
+            sum = _a + _b;
+        }
+    }
+
+Function parameters can be used as any other local variable and they can also be assigned to.
+
+.. note::
+
+  An :ref:`external function<external-function-calls>` cannot accept a
+  multi-dimensional array as an input
+  parameter. This functionality is possible if you enable the new
+  experimental ``ABIEncoderV2`` feature by adding ``pragma experimental ABIEncoderV2;`` to your source file.
+
+  An :ref:`internal function<external-function-calls>` can accept a
+  multi-dimensional array without enabling the feature.
+
+.. index:: return array, return string, array, string, array of strings, dynamic array, variably sized array, return struct, struct
+
+Return Variables
+----------------
+
+Function return variables are declared with the same syntax after the
+``returns`` keyword.
+
+For example, suppose you want to return two results: the sum and the product of
+two integers passed as function parameters, then you use something like::
+
+    pragma solidity >=0.4.16 <0.6.0;
+
+    contract Simple {
+        function arithmetic(uint _a, uint _b)
+            public
+            pure
+            returns (uint o_sum, uint o_product)
+        {
+            o_sum = _a + _b;
+            o_product = _a * _b;
+        }
+    }
+
+The names of return variables can be omitted.
+Return variables can be used as any other local variable and they
+are initialized with their :ref:`default value <default-value>` and have that value unless explicitly set.
+
+You can either explicitly assign to return variables and
+then leave the function using ``return;``,
+or you can provide return values
+(either a single or :ref:`multiple ones<multi-return>`) directly with the ``return``
+statement::
+
+    pragma solidity >=0.4.16 <0.6.0;
+
+    contract Simple {
+        function arithmetic(uint _a, uint _b)
+            public
+            pure
+            returns (uint o_sum, uint o_product)
+        {
+            return (_a + _b, _a * _b);
+        }
+    }
+
+This form is equivalent to first assigning values to the
+return variables and then using ``return;`` to leave the function.
+
+.. note::
+    You cannot return some types from non-internal functions, notably
+    multi-dimensional dynamic arrays and structs. If you enable the
+    new experimental ``ABIEncoderV2`` feature by adding ``pragma experimental
+    ABIEncoderV2;`` to your source file then more types are available, but
+    ``mapping`` types are still limited to inside a single contract and you
+    cannot transfer them.
+
+.. _multi-return:
+
+Returning Multiple Values
+-------------------------
+
+When a function has multiple return types, the statement ``return (v0, v1, ..., vn) can be used to return multiple values.
+vn)`` can return multiple values.  The number of components must be
+the same as the number of return types.
+
 .. index:: ! view function, function;view
 
 .. _view-functions:

docs/control-structures.rst

@@ -4,100 +4,6 @@ Expressions and Control Structures
 
 .. index:: ! parameter, parameter;input, parameter;output, function parameter, parameter;function, return variable, variable;return, return
 
-Function Parameters and Return Variables
-========================================
-
-As in JavaScript, functions may take parameters as input. Unlike in JavaScript
-and C, functions may also return an arbitrary number of values as output.
-
-Function Parameters
--------------------
-
-Function parameters are declared the same way as variables, and the name of
-unused parameters can be omitted.
-
-For example, if you want your contract to accept one kind of external call
-with two integers, you would use something like::
-
-    pragma solidity >=0.4.16 <0.6.0;
-
-    contract Simple {
-        uint sum;
-        function taker(uint _a, uint _b) public {
-            sum = _a + _b;
-        }
-    }
-
-Function parameters can be used as any other local variable and they can also be assigned to.
-
-.. note::
-
-  An :ref:`external function<external-function-calls>` cannot accept a
-  multi-dimensional array as an input
-  parameter. This functionality is possible if you enable the new
-  experimental ``ABIEncoderV2`` feature by adding ``pragma experimental ABIEncoderV2;`` to your source file.
-
-  An :ref:`internal function<external-function-calls>` can accept a
-  multi-dimensional array without enabling the feature.
-
-.. index:: return array, return string, array, string, array of strings, dynamic array, variably sized array, return struct, struct
-
-Return Variables
-----------------
-
-Function return variables are declared with the same syntax after the
-``returns`` keyword.
-
-For example, suppose you want to return two results: the sum and the product of
-two integers passed as function parameters, then you use something like::
-
-    pragma solidity >=0.4.16 <0.6.0;
-
-    contract Simple {
-        function arithmetic(uint _a, uint _b)
-            public
-            pure
-            returns (uint o_sum, uint o_product)
-        {
-            o_sum = _a + _b;
-            o_product = _a * _b;
-        }
-    }
-
-The names of return variables can be omitted.
-Return variables can be used as any other local variable and they
-are initialized with their :ref:`default value <default-value>` and have that value unless explicitly set.
-set, they stay zero value.
-
-You can either explicitly assign to return variables and
-then leave the function using ``return;``,
-or you can provide return values
-(either a single or :ref:`multiple ones<multi-return>`) directly with the ``return``
-statement::
-
-    pragma solidity >=0.4.16 <0.6.0;
-
-    contract Simple {
-        function arithmetic(uint _a, uint _b)
-            public
-            pure
-            returns (uint o_sum, uint o_product)
-        {
-            return (_a + _b, _a * _b);
-        }
-    }
-
-This form is equivalent to first assigning values to the
-return variables and then using ``return;`` to leave the function.
-
-
-.. note::
-    You cannot return some types from non-internal functions, notably
-    multi-dimensional dynamic arrays and structs. If you enable the
-    new experimental ``ABIEncoderV2`` feature by adding ``pragma experimental
-    ABIEncoderV2;`` to your source file then more types are available, but
-    ``mapping`` types are still limited to inside a single contract and you
-    cannot transfer them.
 
 .. index:: if, else, while, do/while, for, break, continue, return, switch, goto
 
@@ -116,15 +22,6 @@ Note that there is no type conversion from non-boolean to boolean types as
 there is in C and JavaScript, so ``if (1) { ... }`` is *not* valid
 Solidity.
 
-.. _multi-return:
-
-Returning Multiple Variables
-----------------------------
-
-When a function has multiple return types, ``return (v0, v1, ...,
-vn)`` can return multiple values.  The number of components must be
-the same as the number of return types.
-
 .. index:: ! function;call, function;internal, function;external
 
 .. _function-calls: