Commit 40d6bb59 authored by Robert Griesemer's avatar Robert Griesemer

- book-keeping in the TODO section:

  - removed closed, resolved, or off-the-table items
  - consolidated remaining items
- no changes to the spec

R=r
DELTA=116  (1 added, 102 deleted, 13 changed)
OCL=27596
CL=27640
parent 0dd5be48
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Biggest open issues:
[ ] General iterators
Open issues:
[ ] Semantics of type declaration:
- creating a new type (status quo), or only a new type name?
- also: declaration type T S; strips methods of S. why/why not?
Decisions in need of integration into the doc:
[ ] pair assignment is required to get map, and receive ok.
[ ] len() returns an int, new(array_type, n) n must be an int
- declaration "type T S" strips methods of S. why/why not?
- no mechanism to declare a local type name: type T P.T
Todo's:
[ ] document illegality of package-external tuple assignments to structs
w/ private fields: P.T(1, 2) illegal since same as P.T(a: 1, b: 2) for
a T struct { a b int }.
[ ] clarification on interface types, rules
[ ] clarify tuples
[ ] need to talk about precise int/floats clearly
[ ] iant suggests to use abstract/precise int for len(), cap() - good idea
(issue: what happens in len() + const - what is the type?)
[ ] fix "else" part of if statement
[ ] cleanup: 6g allows: interface { f F } where F is a function type.
fine, but then we should also allow: func f F {}, where F is a function type.
[ ] decide if and what to write about evaluation order of tuple assignments
[ ] should probably write something about evaluation order of statements even
though obvious
[ ] string conversion: string([]int{}) vs string(int) conversion. Former is
"inverse" of string range iteration.
[ ] do we need explicit channel conversion (to change channel direction)?
Wish list:
[ ] enum facility (enum symbols that are not mixable with ints) or some other
mechanism to obtain type-safety which we don't have with int-only tags
[ ] Gri: built-in assert() - alternatively: allow entire expressions
as statements so we can write: some_condition || panic(); (along these lines)
[ ] enum symbols that are not mixable with ints or some other mechanism
(requirement that basic type aliases need conversion for compatibility)
[ ] Helper syntax for composite types: allow names/keys/indices for
structs/maps/arrays, remove need for type in elements of composites
Smaller issues:
[ ] do we need channel conversion (channel direction)
Closed:
[x] Russ: If we use x.(T) for all conversions, we could use T() for "construction"
and type literals - would resolve the parsing ambiguity of T{} in if's -
switching to () for literals, conversion discussion still open
[x] Russ: consider re-introducing "func" for function type. Make function literals
behave like slices, etc. Require no &'s to get a function value (solves issue
of func{} vs &func{} vs &func_name).
[x] onreturn/undo statement - now: defer statement
[x] comparison of non-basic types: what do we allow? what do we allow in interfaces
what about maps (require ==, copy and hash)
maybe: no maps with non-basic type keys, and no interface comparison unless
with nil[x]
[x] clarify slice rules
[x] what are the permissible ranges for the indices in slices? The spec
doesn't correspond to the implementation. The spec is wrong when it
comes to the first index i: it should allow (at least) the range 0 <= i <= len(a).
also: document different semantics for strings and arrays (strings cannot be grown).
[x] reopening & and func issue: Seems inconsistent as both &func(){} and func(){} are
permitted. Suggestion: func literals are pointers. We need to use & for all other
functions. This would be in consistency with the declaration of function pointer
variables and the use of '&' to convert methods into function pointers.
- covered by other entry
[x] composite types should uniformly create an instance instead of a pointer - fixed
[x] like to have assert() in the language, w/ option to disable code gen for it
- added to wish list
[x] convert should not be used for composite literals anymore,
in fact, convert() should go away - made a todo
[x] provide composite literal notation to address array indices: []int{ 0: x1, 1: x2, ... }
and struct field names (both seem easy to do). - under "Missing" list
[x] passing a "..." arg to another "..." parameter doesn't wrap the argument again
(so "..." args can be passed down easily) - this is documented
[x] consider syntactic notation for composite literals to make them parsable w/o type information
(require ()'s in control clauses) - use heuristics for now
[x] do we need anything on package vs file names? - current package scheme workable for now
[x] what is the meaning of typeof() - we don't have it
[x] old-style export decls (still needed, but ideally should go away)
[x] packages of multiple files - we have a working approach
[x] partial export of structs, methods
[x] new as it is now is weird - need to go back to previous semantics and introduce
literals for slices, maps, channels - done
[x] determine if really necessary to disallow array assignment - allow array assignment
[x] semantics of statements - we just need to fill in the language, the semantics is mostly clear
[x] range statement: to be defined more reasonably
[x] need to be specific on (unsigned) integer operations: one must be able
to rely on wrap-around on overflow
[x] global var decls: "var a, b, c int = 0, 0, 0" is ok, but "var a, b, c = 0, 0, 0" is not
(seems inconsistent with "var a = 0", and ":=" notation)
[x] const decls: "const a, b = 1, 2" is not allowed - why not? Should be symmetric to vars.
[x] 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) - documented
[x] should we have a shorter list of alias types? (byte, int, uint, float) - done
[x] reflection support
[x] syntax for var args
[x] Do composite literals create a new literal each time (gri thinks yes) (Russ is putting in a change
to this effect, essentially)
[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.
this might be a problem when referring to such a field using the type name.
[x] nil and interfaces - can we test for nil, what does it mean, etc.
[x] talk about underflow/overflow of 2's complement numbers (defined vs not defined).
[x] change wording on array composite literals: the types are always fixed arrays
for array composites
[x] meaning of nil
[x] remove "any"
[x] methods for all types
[x] should binary <- be at lowest precedence level? when is a send/receive non-blocking? (NO - 9/19/08)
[x] func literal like a composite type - should probably require the '&' to get address (NO)
[x] & needed to get a function pointer from a function? (NO - there is the "func" keyword - 9/19/08)
[x] Conversions:
- current situation is messy
- 2 (3?) different notations for the same thing
- unclear when a type assertion is needed
- unclear where conversions can be applied
- for type T int; can we say T(3.0) ?
[x] need for type switch? (or use type assertion with ok in tuple assignment?)
[x] Is . import implemented / do we still need it?
[x] Do we allow empty statements? If so, do we allow empty statements after a label?
and if so, does a label followed by an empty statement (a semicolon) still denote
a for loop that is following, and can break L be used inside it?
[x] there is some funniness regarding ';' and empty statements and label decls
[x] cleanup convert() vs T() vs x.(T) - convert() should go away?
[x] decide if and what to write about evaluation order of composite literal
elements (single expressions, (key:value) pairs)
structs/maps/arrays
[ ] built-in assert() ("conditional panic") (gri)
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<h2>Introduction</h2>
<p>
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