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- added language re: interface compparison using ==, !=

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(seems not controversial)

R=r
DELTA=8  (3 added, 2 deleted, 3 changed)
OCL=16940
CL=16940
This commit is contained in:
Robert Griesemer 2008-10-10 16:34:44 -07:00
parent 900e076d21
commit b5e0cc7ef5
1 changed files with 6 additions and 5 deletions
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11
doc/go_spec.txt
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@ -54,7 +54,6 @@ Open issues:
[ ] new(arraytype, n1, n2): spec only talks about length, not capacity
(should only use new(arraytype, n) - this will allow later
extension to multi-dim arrays w/o breaking the language)
[ ] comparison operators: can we compare interfaces?
[ ] like to have assert() in the language, w/ option to disable code gen for it
[ ] composite types should uniformly create an instance instead of a pointer
[ ] semantics of statements
@ -85,6 +84,7 @@ Decisions in need of integration into the doc:
Closed:
[x] comparison operators: can we compare interfaces?
[x] can we add methods to types defined in another package? (probably not)
[x] optional semicolons: too complicated and unclear
[x] anonymous types are written using a type name, which can be a qualified identifier.
@ -1348,7 +1348,7 @@ number of methods with the same names, and corresponding (by name) methods
have the same function types.
Assignment compatibility: A value can be assigned to an interface variable
if the static type of the value implements the interface.
if the static type of the value implements the interface or if the value is "nil".
Expressions
@ -1810,8 +1810,7 @@ Comparison operators
Comparison operators yield a boolean result. All comparison operators apply
to strings and numeric types. The operators "==" and "!=" also apply to
boolean values and to pointer types (including the value "nil"). Finally,
"==" and "!=" can also be used to compare interface types against "nil".
boolean values, pointer and interface types (including the value "nil").
== equal
!= not equal
@ -1822,7 +1821,9 @@ boolean values and to pointer types (including the value "nil"). Finally,
Strings are compared byte-wise (lexically).
Interfaces can be tested against "nil" (§Interface types).
Pointers are equal if they point to the same value.
Interfaces are equal if both their dynamic types and values are equal.
For a value "v" of interface type, "v == nil" is true only if the predeclared
constant "nil" is assigned explicitly to "v" (§Assignments), or "v" has not
been modified since creation (§Program initialization and execution).