Skip to content

Runtime assertions with binding.assert #341

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
joeldrapper wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Runtime assertions with binding.assert #341

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
379a078
Binding assertions
joeldrapper Oct 16, 2025
2b6d370
Update lib/literal.rb
joeldrapper Oct 19, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
44 changes: 44 additions & 0 deletions lib/literal.rb
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,50 @@ module Literal
loader.setup
end

CLASS_METHOD = Kernel.instance_method(:class)
CLASS_VARIABLE_GET_METHOD = Module.instance_method(:class_variable_get)
INSTANCE_VARIABLE_GET_METHOD = Kernel.instance_method(:instance_variable_get)

module BindingAssert
def assert(...) = Literal.assert(self, ...)
end

::Binding.include(Literal::BindingAssert)
Copy link
Collaborator Author

@joeldrapper joeldrapper Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We should make a literal/pure entry point that people can use if they want to opt out of patches.

Copy link
Collaborator

@stevegeek stevegeek Oct 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Personally would rather opt-in than opt-out, eg literal/binding_assert

Copy link
Collaborator

@fractaledmind fractaledmind Oct 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Elaborate? It has no perf cost, no overhead. And this DX is superior to Literal.assert(binding, **constraints).

Copy link
Collaborator

@stevegeek stevegeek Oct 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It is mixing something in Binding, which I would find somewhat unexpected unless I explicitly wanted that feature

Copy link
Collaborator Author

@joeldrapper joeldrapper Oct 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think the main use case will be people opting in. I was only thinking of adding /pure for gem authors who might not want a transient dependency to do patching.



def self.assert(bind, **kwargs)
kwargs.each do |name, type|
string_name = (Symbol === name) ? name.name : name
first_byte = string_name.getbyte(0)

if first_byte == 64 # @foo
if string_name.getbyte(1) == 64 # @@foo
value = CLASS_VARIABLE_GET_METHOD.bind_call(
CLASS_METHOD.bind_call(bind.receiver), name
)
else # @foo
value = INSTANCE_VARIABLE_GET_METHOD.bind_call(bind.receiver, name)
end
elsif first_byte == 36 # $foo
raise if string_name.match?(/[\s\.]/)
Copy link
Collaborator

@fractaledmind fractaledmind Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Need to raise a named exception here with a clear message.

value = eval(string_name)
else # foo
value = bind.local_variable_get(name)
end

unless type === value
raise ::TypeError.new(<<~MESSAGE)
Copy link
Collaborator

@fractaledmind fractaledmind Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Joel and I discussed that Literal::TypeError needs a refactor to be more generic to allow for simpler errors like this. Personally, I think make TypeError simple like this and move the property stuff into a PropertyError class that inherits from TypeError

Copy link
Collaborator

@stevegeek stevegeek Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Great idea

Assertion failed!

#{name}
Expected: #{type.inspect}
Actual (#{value.class}): #{value.inspect}
MESSAGE
end
end
end


def self.Value(*args, **kwargs, &block)
value_class = Class.new(Literal::Value)

Expand Down
50 changes: 50 additions & 0 deletions test/assert.test.rb
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
$a = 1

test "assert with local variable" do
refute_raises do
a = 1
b = "Hello"

binding.assert(a: Integer, b: String)
binding.assert("a" => Integer, "b" => String)
end

assert_raises TypeError do
a = 1
binding.assert(a: String)
end
end

test "assert with global variable" do
refute_raises do
binding.assert("$a": Integer)
end

assert_raises TypeError do
binding.assert("$a": String)
end
end

test "assert with instance variable" do
refute_raises do
@a = 1
binding.assert("@a": Integer)
end

assert_raises TypeError do
@a = 1
binding.assert("@a": String)
end
end

test "assert with class variable" do
refute_raises do
@@a = 1
binding.assert("@@a": Integer)
end

assert_raises TypeError do
@@a = 1
binding.assert("@@a": String)
end
end
Loading