text/template: method discovery

[gopherbot]

by tux21b:

The Go compiler automatically takes the address of a value V when a method is called
which is defined on a *V receiver. The "text/template" package should do the
same.

See the attached example for further details.

https://groups.google.com/d/msg/golang-nuts/eKSiPCAalMQ/O5JpDk8QpxUJ

Attachments:

1. autodiscover.go (681 bytes)

[adg]

Comment 1:

Labels changed: added priority-soon, removed priority-triage.

Owner changed to @robpike.

Status changed to Accepted.

[robpike]

Comment 2:

Despite my "first blush" comment, this is not a bug. The template package handles this
correctly.
The example here is a textbook version of the 'settability' issue described near the end
of the "Laws of Reflection" blog post:
http://blog.golang.org/2011/09/laws-of-reflection.html.
When p2 is passed to the template library, the library receives a copy of p2, not p2
itself. It would be incorrect to take its address to discover the method.  Go in general
behaves the same way; if you say p2.X() the compiler can take the address of the local
variable p2, but that's not the same as passing p2 to a function, calling X, and
expecting the original p2 to be updated.
Working as intended, if subtly.

Status changed to WorkingAsIntended.