Re: Questions about parsing boolean and casting to anyelement

From: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Questions about parsing boolean and casting to anyelement
Date: 2009-02-17 00:53:04
Message-ID: 20090217092434.F173.52131E4D@oss.ntt.co.jp
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> > - Are there any limitations in casting to anyelement?
>
> It's a no-op ... probably we shouldn't even let you do it, if the
> lack of an error leaves room for such misinterpretation as this.
> anyelement and friends are placeholders for use in function
> declarations, not real types that it makes sense to cast to.

I hope anyelement could be used in cast because casts are supported by
almost programming languages where template or generics are available.
Moreover, we can cast to anyelement if we use C functions; using oid of
anyelement in runtime and querying an associated cast function from
system catalog.

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center

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