You can write that.
func insert(m map[K]V, k K, v V) map[K]V {
if m == nil {
return map[K]V{k: v}
}
m[k] = v
return m
}
On Tue, 2019-09-24 at 13:10 -0700, Marcin Romaszewicz wrote:
> Could we have an operation like append() for slices?
>
> How about:
>
> m := insert(m, "key", "value").
>
> It returns m unchanged if it's allocated, otherwise, it allocates.
> We're
> already familiar with this kind of function.
>
> -- Marcin
>
> On Mon, Sep 23, 2019 at 10:58 PM abuchanan via golang-nuts <
> [email protected]> wrote:
>
> > Ah, thanks Ian, that's exactly the kind of requirement I was
> > looking for.
> >
> > (also, you said "without" but you probably meant "while")
> >
> > Perhaps this is a job for "go vet". And/or, looks like
> > staticcheck.io has
> > a check I can try: https://staticcheck.io/docs/checks#SA5000
> >
> >
> >
> >
> >
> > On Monday, September 23, 2019 at 9:45:37 PM UTC-7, Ian Lance Taylor
> > wrote:
> > >
> > > On Mon, Sep 23, 2019 at 2:40 PM abuchanan via golang-nuts
> > > <[email protected]> wrote:
> > > >
> > > > Is there anything written down on why assignment to a nil map
> > > > causes a
> > >
> > > panic? I'm curious if there were carefully considered tradeoffs
> > > while
> > > making this decision.
> > > >
> > > > Assignment to nil maps has caused most of the unexpected panics
> > > > I've
> > >
> > > seen. Many times these happen in production and cause an
> > > incident. Every
> > > time it happens I think, "we've got to do something about this."
> > > >
> > > > I'm not sure what the best solution is yet, but there must be
> > > > something
> > >
> > > better than the status quo. Would it be possible to have
> > > assignments
> > > automatically initialize a nil map?
> > >
> > > I agree that this is awkward. But we've never been able to think
> > > of a
> > > way to make an assignment to a nil map initialize the map without
> > > also
> > > preserving the very useful property that the zero value of any Go
> > > type
> > > can be represented by a sequence of zero bytes.
> > >
> > > Ian
> > >
> >
> > --
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> > Groups
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> > send an
> > email to [email protected].
> > To view this discussion on the web visit
> >
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> > <
> > https://groups.google.com/d/msgid/golang-nuts/d9cc8fb3-7d73-48c0-8c60-9d9b1022054c%40googlegroups.com?utm_medium=email&utm_source=footer
> > >
> > .
> >
>
>
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