I have read it several times. From my little experience, I think you mean: - the `args` is defined inside the macro quote context, and used in the caller context where the quote expands to? - and that's why var! comes to rescue?
在 2016年7月29日星期五 UTC+8上午2:23:41，Eric Meadows-Jönsson写道： > > It's documented under "Hygiene for variables" here > http://elixir-lang.org/docs/stable/elixir/Kernel.SpecialForms.html#quote/2 > . > > The reasoning for this behaviour is that variables from different contexts > shouldn't leak into each others contexts without making it explicit with > `var!`. > > Your code doesn't work because `args` is used in a different context than > where it was defined. > > On Wed, Jul 27, 2016 at 3:28 PM, Jiafeng Cao <[email protected] > <javascript:>> wrote: > >> Hi, I've been reading through about macros, and came across the `var!`. I >> thought I got the idea of it until I wrote some code like this gist >> <https://www.google.com/url?q=https%3A%2F%2Fgist.github.com%2Flerencao%2F9a271ba31b6771f4563f645fae9b9815&sa=D&sntz=1&usg=AFQjCNE6d_LJEsmjXn0xoBrupBSkwIaXYg> >> . >> I know I can use `def unquote(name)(var!(args)), do: ...` to make it >> work. I just cannot get it. >> What's I missing here? Many thanks. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-talk" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-talk/09af6955-28e3-4a14-8851-0bfa201dc760%40googlegroups.com >> >> <https://groups.google.com/d/msgid/elixir-lang-talk/09af6955-28e3-4a14-8851-0bfa201dc760%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Eric Meadows-Jönsson > -- You received this message because you are subscribed to the Google Groups "elixir-lang-talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-talk/2f17fe5e-6db7-4b3d-858c-41a6fd50aa0c%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
