Pretty-print values in the REPL by printing each item in a list or
attrset on a separate line. When possible, single-item lists and
attrsets are printed on one line, as long as they don't contain a nested
list, attrset, or thunk.
Before:
```
{ attrs = { a = { b = { c = { }; }; }; }; list = [ 1 ]; list' = [ 1 2 3 ]; }
```
After:
```
{
attrs = {
a = {
b = {
c = { };
};
};
};
list = [ 1 ];
list' = [
1
2
3
];
}
```
(cherry picked from commit c0a15fb7d03dfb8f53bc6726c414bc88aa362592)
Change-Id: Ia2b41849165a5ddb63f7a8c272a2476b3e4292df
Print the value in `error: cannot coerce` messages
(cherry picked from commit 5b7bfd2d6b89d7dd5f54c1ca6c8072358d31a84e)
===
test taken from 6e8d5983143ae576e3f4b1d2954a5267f2943a49; it was added
previously (and not backported because its pr was a mostly-revert), but
it's useful to have around.
Change-Id: Icbd14b55e3610ce7b774667bf14b82e6dc717982
Previously, there were two mostly-identical value printers -- one in
`libexpr/eval.cc` (which didn't force values) and one in
`libcmd/repl.cc` (which did force values and also printed ANSI color
codes).
This PR unifies both of these printers into `print.cc` and provides a
`PrintOptions` struct for controlling the output, which allows for
toggling whether values are forced, whether repeated values are tracked,
and whether ANSI color codes are displayed.
Additionally, `PrintOptions` allows tuning the maximum number of
attributes, list items, and bytes in a string that will be displayed;
this makes it ideal for contexts where printing too much output (e.g.
all of Nixpkgs) is distracting. (As requested by @roberth in
https://github.com/NixOS/nix/pull/9554#issuecomment-1845095735)
Please read the tests for example output.
Future work:
- It would be nice to provide this function as a builtin, perhaps
`builtins.toStringDebug` -- a printing function that never fails would
be useful when debugging Nix code.
- It would be nice to support customizing `PrintOptions` members on the
command line, e.g. `--option to-string-max-attrs 1000`.
(cherry picked from commit 0fa08b451682fb3311fe58112ff05c4fe5bee3a4, )
===
Restore ambiguous value printer for `nix-instantiate`
The Nix team has requested that this output format remain unchanged.
I've added a warning to the man page explaining that `nix-instantiate
--eval` output will not parse correctly in many situations.
(cherry picked from commit df84dd4d8dd3fd6381ac2ca3064432ab31a16b79)
Change-Id: I7cca6b4b53cd0642f2d49af657d5676a8554c9f8
Today, with the tests inside a `tests` intermingled with the
corresponding library's source code, we have a few problems:
- We have to be careful that wildcards don't end up with tests being
built as part of Nix proper, or test headers being installed as part
of Nix proper.
- Tests in libraries but not executables is not right:
- It means each executable runs the previous unit tests again, because
it needs the libraries.
- It doesn't work right on Windows, which doesn't want you to load a
DLL just for the side global variable . It could be made to work
with the dlopen equivalent, but that's gross!
This reorg solves these problems.
There is a remaining problem which is that sibbling headers (like
`hash.hh` the test header vs `hash.hh` the main `libnixutil` header) end
up shadowing each other. This PR doesn't solve that. That is left as
future work for a future PR.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
(cherry picked from commit 91b6833686a6a6d9eac7f3f66393ec89ef1d3b57)
(cherry picked from commit a61e42adb528b3d40ce43e07c79368d779a8b624)
eldritch horrors
