Feature #6733
openNew inspect framework
Description
After we discussed http://bugs.ruby-lang.org/issues/6291 at a developer meeting,
we re-realized new inspect framework may be useful.
Problem:
- inspect method may generate too long string but sometimes whole string is not required.
For example, first 70 characters are enough for error messages (backtrace). - inspect can't know a encoding to be expected.
- inspect generates may short strings and discard them immediately.
If we have a new method, inspect_to(buffer), and
it (or overridden method in subclass) adds the inspected result to buffer,
we can solve above problems.
buffer has a method, <<.
It may be a string, IO or other object.
For too long string, buffer itself can throw (or raise) when buffered output is reached to a specified limit.
For encoding, buffer can record an encoding.
(p method creates a buffer object using $stdout's encoding.)
For small strings, in C level, we can create a rb_buffer_add(VALUE buffer, const char *p, long len) and
it don't need to allocate a String object.
This is big change but we can preserve compatibility by following default inspect_to method:
class Object
def inspect_to(buffer)
buffer << self.inspect
end
end
If legacy class which has inspect but not inspect_to,
Object#inspect_to calls inspect and use the result.
Updated by Anonymous over 11 years ago
Thank you so much for this. Whenever I use #inspect and #to_s methods, such as when writing
puts "blah blah #{object} blah"
I cannot help but be afraid that object's #to_s method will return 20MB string, that will overrun something somewhere and take control over my computer :-)
Updated by Anonymous over 11 years ago
Call me a paranoid, if you want :-)
Updated by shyouhei (Shyouhei Urabe) almost 8 years ago
- Related to Feature #6783: Infinite loop in inspect, not overriding inspect, to_s, and no known circular references. Stepping into inspect in debugger locks it up with 100% CPU. added
Updated by mame (Yusuke Endoh) over 2 years ago
- Related to Feature #18285: NoMethodError#message uses a lot of CPU/is really expensive to call added
Updated by mame (Yusuke Endoh) over 2 years ago
I like this proposal.
Updated by kou (Kouhei Sutou) over 2 years ago
This may be out-of-scope but I hope that this mechanism also supports multimedia like Julia: https://docs.julialang.org/en/v1/base/io-network/#Multimedia-I/O
My use case is showing images on irb automatically.
For example with Red Datasets and Charty:
irb(main):001:0> require "datasets"
=> true
irb(main):002:0> require "charty"
=> true
irb(main):003:0> penguins = Datasets::Penguins.new
=>
#<Datasets::Penguins:0x00007f308dd34d10
...
irb(main):004:0> Charty.scatter_plot(data: penguins, x: :body_mass_g, y: :flipper_length_mm, color: :species)
=> #<Charty::Plotters::ScatterPlotter:0x0000000000000424> # Show Sixel images here if the terminal supports Sixel
ref: Sixel
Updated by Eregon (Benoit Daloze) over 2 years ago
Should the (remaining) limit (of nb of characters) be passed to inspect_to
?
Otherwise if the logic is like creating a long string, and then appending to the buffer, we have the problem that it still takes a long time and might waste a lot of needless computation.
Updated by Dan0042 (Daniel DeLorme) over 2 years ago
This sounds like a very powerful and flexible approach, but perhaps a little over-engineered?
Maybe a more KISS approach would be sufficient; just define Object#simple_inspect
to be used when we need a short string, like in NoMethodError#message
.
By default it can return #<MyClass:0x00007fe40a128ae0>
(without ivars).
Updated by mame (Yusuke Endoh) over 2 years ago
Eregon (Benoit Daloze) wrote in #note-8:
Should the (remaining) limit (of nb of characters) be passed to
inspect_to
?
Otherwise if the logic is like creating a long string, and then appending to the buffer, we have the problem that it still takes a long time and might waste a lot of needless computation.
I don't think that your concern will be addressed even if limit is passed. The logic can still create a long string and then truncate it to fit with the limit. inspect_to
should append small strings to the buffer, which should be noted as a best practice.
Dan0042 (Daniel DeLorme) wrote in #note-9:
This sounds like a very powerful and flexible approach, but perhaps a little over-engineered?
Maybe a more KISS approach would be sufficient; just defineObject#simple_inspect
to be used when we need a short string, like inNoMethodError#message
.
Indeed this proposal was unearthed in the context of NoMethodError#message
(#18285), but the use case is not limited to that.