Class: Handshake::Proxy
- Inherits:
-
Object
- Object
- Handshake::Proxy
- Defined in:
- lib/handshake.rb
Overview
This class filters all method calls to its proxied object through any contracts defined on that object’s class. It attempts to look and act like its proxied object for all intents and purposes, although it notably does not proxy __id__
, __send__
, or class
.
Constant Summary collapse
- NOT_PROXIED =
[ "__id__", "__send__" ]
- SELF_PROXIED =
Object.instance_methods - NOT_PROXIED
Instance Method Summary collapse
-
#initialize(proxied) ⇒ Proxy
constructor
Accepts an object to be proxied.
-
#proxied_class ⇒ Object
Returns the class of the proxied object.
-
#send(meth_name, *args, &block) ⇒ Object
(also: #method_missing)
Override the send method, and alias method_missing to same.
-
#unchecked! ⇒ Object
Returns the wrapped object.
Constructor Details
#initialize(proxied) ⇒ Proxy
Accepts an object to be proxied.
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# File 'lib/handshake.rb', line 516 def initialize(proxied) @proxied = proxied end |
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing ⇒ Object
Override the send method, and alias method_missing to same. This method intercepts all method calls and runs them through the contract filter. The order of contract checks is as follows:
-
Before: invariants, method signature, precondition
-
Method is called
-
After: method signature, postcondition, invariants
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# File 'lib/handshake.rb', line 567 def send(meth_name, *args, &block) meth_string = "#{@proxied.class}##{meth_name}" contract = @proxied.class.contract_for(meth_name) return_val = nil # Use throw/catch rather than raise/rescue in order to pull exceptions # once and only once from within the stack trace. Handshake.catch_contract("Contract violated in call to #{meth_string}") do @proxied.check_invariants! contract.check_accepts! *args, &block contract.check_pre! @proxied, *args end # make actual call, wrapping the given block in a new block so that # contract checks work if receiver uses yield. return_val = nil if contract.expects_block? block.contract = contract.block_contract return_val = @proxied.send(meth_name, *args) { |*argz| block.call(*argz) } else return_val = @proxied.send(meth_name, *args, &block) end Handshake.catch_contract("Contract violated by #{meth_string}") do contract.check_returns! return_val contract.check_post! @proxied, *(args << return_val) @proxied.check_invariants! end return return_val end |
Instance Method Details
#proxied_class ⇒ Object
Returns the class of the proxied object.
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# File 'lib/handshake.rb', line 527 def proxied_class @proxied.class end |
#send(meth_name, *args, &block) ⇒ Object Also known as: method_missing
Override the send method, and alias method_missing to same. This method intercepts all method calls and runs them through the contract filter. The order of contract checks is as follows:
-
Before: invariants, method signature, precondition
-
Method is called
-
After: method signature, postcondition, invariants
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# File 'lib/handshake.rb', line 537 def send(meth_name, *args, &block) meth_string = "#{@proxied.class}##{meth_name}" contract = @proxied.class.contract_for(meth_name) return_val = nil # Use throw/catch rather than raise/rescue in order to pull exceptions # once and only once from within the stack trace. Handshake.catch_contract("Contract violated in call to #{meth_string}") do @proxied.check_invariants! contract.check_accepts! *args, &block contract.check_pre! @proxied, *args end # make actual call, wrapping the given block in a new block so that # contract checks work if receiver uses yield. return_val = nil if contract.expects_block? block.contract = contract.block_contract return_val = @proxied.send(meth_name, *args) { |*argz| block.call(*argz) } else return_val = @proxied.send(meth_name, *args, &block) end Handshake.catch_contract("Contract violated by #{meth_string}") do contract.check_returns! return_val contract.check_post! @proxied, *(args << return_val) @proxied.check_invariants! end return return_val end |
#unchecked! ⇒ Object
Returns the wrapped object. Method calls made against this object will not be checked.
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# File 'lib/handshake.rb', line 522 def unchecked! @proxied end |