Re: [RFC] Introduce Abstract Syntax Tree

Michael Wallner wrote: > On 14 08 2014, at 11:33, Alain Williams <addw@phcomp.co.uk> wrote: > >> It is OK to define some things as undefined and have them break between releases - >> even minor releases. I always teach it as undefined - as it is in most >> programming languages. >> >> Likewise, if the next 2 characters on input are 'a' then 'b' what gets >> assigned >> could either be 'ab' or 'ba': >> >> $TwoChars = fgetc($in) . fgetc($in); >> >> Some code is just broken. > > Wat? No. This is totally different to two in/decrements on one line. This has to be executed in > order. The current specification draft says[1]: | Unless stated explicitly in this specification, the order in which | the operands in an expression are evaluated relative to each other is | unspecified. | [...] | Finally, in the full expression f() + g() * h(), the order in which | the three functions are called, is unspecified). [1] <https://github.com/php/php-langspec/blob/master/spec/10-expressions.md#expressions> -- Christoph M. Becker