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spec: receiver declaration is just a parameter declaration
This CL removes the special syntax for method receivers and makes it just like other parameters. Instead, the crucial receiver-specific rules (exactly one receiver, receiver type must be of the form T or *T) are specified verbally instead of syntactically. This is a fully backward-compatible (and minor) syntax relaxation. As a result, the following syntactic restrictions (which are completely irrelevant) and which were only in place for receivers are removed: a) receiver types cannot be parenthesized b) receiver parameter lists cannot have a trailing comma The result of this CL is a simplication of the spec and the implementation, with no impact on existing (or future) code. Noteworthy: - gc already permits a trailing comma at the end of a receiver declaration: func (recv T,) m() {} This is technically a bug with the current spec; this CL will legalize this notation. - gccgo produces a misleading error when a trailing comma is used: error: method has multiple receivers (even though there's only one receiver) - Compilers and type-checkers won't need to report errors anymore if receiver types are parenthesized. Fixes #4496. LGTM=iant, rsc R=r, rsc, iant, ken CC=golang-codereviews https://golang.org/cl/101500044
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@ -1,6 +1,6 @@
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<!--{
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"Title": "The Go Programming Language Specification",
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"Subtitle": "Version of May 28, 2014",
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"Subtitle": "Version of June 24, 2014",
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"Path": "/ref/spec"
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}-->
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@ -2029,13 +2029,14 @@ and associates the method with the receiver's <i>base type</i>.
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<pre class="ebnf">
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MethodDecl = "func" Receiver MethodName ( Function | Signature ) .
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Receiver = "(" [ identifier ] [ "*" ] BaseTypeName ")" .
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BaseTypeName = identifier .
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Receiver = Parameters .
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</pre>
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<p>
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The receiver type must be of the form <code>T</code> or <code>*T</code> where
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<code>T</code> is a type name. The type denoted by <code>T</code> is called
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The receiver is specified via an extra parameter section preceeding the method
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name. That parameter section must declare a single parameter, the receiver.
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Its type must be of the form <code>T</code> or <code>*T</code> (possibly using
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parentheses) where <code>T</code> is a type name. The type denoted by <code>T</code> is called
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the receiver <i>base type</i>; it must not be a pointer or interface type and
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it must be declared in the same package as the method.
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The method is said to be <i>bound</i> to the base type and the method name
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