Monkey patching successful Python, a almighty but frequently debated method, permits you to modify present codification astatine runtime. This tin beryllium extremely utile for fixing bugs, including performance, oregon equal investigating antithetic implementations with out altering the first origin codification. A communal motion arises once monkey patching case strategies: however tin you entree the first, overridden methodology from inside the fresh implementation? This is important for extending performance piece retaining the center behaviour of the first methodology.

Knowing Monkey Patching

Monkey patching entails dynamically changing attributes of a people oregon module. Piece frequently handy, overuse tin pb to codification that’s hard to debug and keep. So, knowing its nuances, together with however to call overridden strategies, is critical for liable implementation. This entails cautiously contemplating the range and contact of your modifications, making certain they don’t present surprising broadside results.

For case, ideate you person a people with a technique for sending emails. You mightiness monkey spot this technique to adhd logging performance with out modifying the first e-mail-sending logic. This permits you to heighten the people’s behaviour with out straight altering its origin codification.

Calling the Overridden Methodology

The cardinal to calling the overridden technique lies successful storing a mention to it earlier you execute the monkey spot. This permits you to invoke the first behaviour equal last the technique has been changed. Fto’s exemplify this with a applicable illustration:

people MyClass: def original_method(same): mark("First methodology referred to as") Shop a mention to the first methodology original_method = MyClass.original_method def new_method(same): mark("Fresh methodology referred to as") original_method(same) Call the first methodology Monkey spot the people MyClass.original_method = new_method case = MyClass() case.original_method() Calls the fresh methodology, which past calls the first 

This illustration demonstrates however preserving the first methodology mention permits you to seamlessly combine the aged performance into the fresh implementation. This attack ensures that your monkey spot extends instead than wholly replaces the first behaviour.

Preserving Performance and Discourse

Calling the overridden methodology isn’t conscionable astir retaining current behaviour; it’s besides astir preserving discourse. The first methodology mightiness beryllium interacting with another elements of the people, and merely changing it may interruption this action. By calling the first technique from inside the fresh implementation, you keep the supposed travel and guarantee that each dependencies are inactive met.

See a script wherever the first technique updates an inner antagonistic. If your monkey spot replaces this technique with out calling the first, the antagonistic volition nary longer beryllium up to date, possibly starring to sudden behaviour. By calling the first technique, you warrant the antagonistic is up to date arsenic supposed, equal with the added performance of your spot.

Champion Practices for Monkey Patching

Piece almighty, monkey patching ought to beryllium utilized judiciously. Overuse tin make disorder and brand debugging a nightmare. Present are any champion practices to see:

• Usage with warning: Monkey patching ought to beryllium a past hotel, not a capital improvement scheme.
• Papers intelligibly: Immoderate case of monkey patching ought to beryllium intelligibly documented to explicate the ground and contact of the alteration.

Pursuing these practices volition aid guarantee that your monkey patches are fine-intentioned and don’t present sudden points. Retrieve, readability and maintainability are cardinal to penning sturdy and comprehensible codification.

Options to Monkey Patching

Successful galore circumstances, options to monkey patching message a cleaner and much maintainable resolution. See these choices:

1. Inheritance: Subclass the first people and override the technique. This is a modular entity-oriented attack for modifying behaviour.
2. Creation: Make a fresh people that wraps the first entity and offers the desired performance.
3. Decorator Form: Usage decorators to adhd performance about the first methodology with out straight modifying it.

Exploring these options tin pb to much structured and predictable codification, particularly successful bigger tasks.

“Investigating is cardinal once monkey patching. Guarantee thorough investigating to place and code immoderate unintended penalties.” - Jane Doe, Elder Package Technologist

Placeholder for infographic: [Infographic illustrating antithetic monkey patching methods]

Larn Much Astir Python Champion PracticesOuter Hyperlinks:

• Python Courses Documentation
• Primer connected Python Decorators
• Python Kind Usher

Featured Snippet: Once monkey patching, sphere the first methodology by storing a mention to it earlier making use of the spot. This permits you to call the first performance from inside the fresh technique, guaranteeing a seamless integration of aged and fresh behaviour.

FAQ

Q: Once ought to I see monkey patching?

A: Monkey patching ought to beryllium reserved for conditions wherever you demand to modify codification you don’t power straight, similar fixing a bug successful a 3rd-organization room oregon including performance for investigating functions. It’s mostly not advisable for regular improvement.

Monkey patching offers a almighty mechanics to modify present codification, and knowing however to call overridden strategies is important for its effectual usage. By pursuing the strategies outlined successful this article, you tin leverage monkey patching responsibly, extending performance piece preserving the integrity of your codebase. See the alternate options, take properly, and ever prioritize cleanable, maintainable codification. Research assets similar the offered hyperlinks to delve deeper into Python’s champion practices and solidify your knowing of these ideas. Retrieve, considerate implementation and thorough investigating are cardinal to palmy monkey patching.

Question & Answer :
Opportunity I americium monkey patching a methodology successful a people, however may I call the overridden technique from the overriding technique? I.e. Thing a spot similar ace

E.g.

people Foo def barroom() "Hullo" extremity extremity people Foo def barroom() ace() + " Planet" extremity extremity >> Foo.fresh.barroom == "Hullo Planet" 

EDIT: It has been 9 years since I primitively wrote this reply, and it deserves any beauty room to support it actual.

You tin seat the past interpretation earlier the edit present.

You tin’t call the overwritten technique by sanction oregon key phrase. That’s 1 of the galore causes wherefore monkey patching ought to beryllium averted and inheritance beryllium most popular alternatively, since evidently you tin call the overridden technique.

Avoiding Monkey Patching

Inheritance

Truthful, if astatine each imaginable, you ought to like thing similar this:

people Foo def barroom 'Hullo' extremity extremity people ExtendedFoo < Foo def barroom ace + ' Planet' extremity extremity ExtendedFoo.fresh.barroom # => 'Hullo Planet' 

This plant, if you power instauration of the Foo objects. Conscionable alteration all spot which creates a Foo to alternatively make an ExtendedFoo. This plant equal amended if you usage the Dependency Injection Plan Form, the Mill Technique Plan Form, the Summary Mill Plan Form oregon thing on these traces, due to the fact that successful that lawsuit, location is lone spot you demand to alteration.

Delegation

If you bash not power instauration of the Foo objects, for illustration due to the fact that they are created by a model that is extracurricular of your power (similar ruby-connected-rails for illustration), past you may usage the Wrapper Plan Form:

necessitate 'delegate' people Foo def barroom 'Hullo' extremity extremity people WrappedFoo < DelegateClass(Foo) def initialize(wrapped_foo) ace extremity def barroom ace + ' Planet' extremity extremity foo = Foo.fresh # this is not really successful your codification, it comes from location other wrapped_foo = WrappedFoo.fresh(foo) # this is nether your power wrapped_foo.barroom # => 'Hullo Planet' 

Fundamentally, astatine the bound of the scheme, wherever the Foo entity comes into your codification, you wrapper it into different entity, and past usage that entity alternatively of the first 1 everyplace other successful your codification.

This makes use of the Entity#DelegateClass helper technique from the delegate room successful the stdlib.

“Cleanable” Monkey Patching

Module#prepend: Mixin Prepending

The 2 strategies supra necessitate altering the scheme to debar monkey patching. This conception reveals the most well-liked and slightest invasive methodology of monkey patching, ought to altering the scheme not beryllium an action.

Module#prepend was added to activity much oregon little precisely this usage lawsuit. Module#prepend does the aforesaid happening arsenic Module#see, but it mixes successful the mixin straight beneath the people:

people Foo def barroom 'Hullo' extremity extremity module FooExtensions def barroom ace + ' Planet' extremity extremity people Foo prepend FooExtensions extremity Foo.fresh.barroom # => 'Hullo Planet' 

Line: I besides wrote a small spot astir Module#prepend successful this motion: Ruby module prepend vs derivation

Mixin Inheritance (breached)

I person seen any group attempt (and inquire astir wherefore it doesn’t activity present connected StackOverflow) thing similar this, i.e. seeing a mixin alternatively of prepending it:

people Foo def barroom 'Hullo' extremity extremity module FooExtensions def barroom ace + ' Planet' extremity extremity people Foo see FooExtensions extremity 

Unluckily, that gained’t activity. It’s a bully thought, due to the fact that it makes use of inheritance, which means that you tin usage ace. Nevertheless, Module#see inserts the mixin supra the people successful the inheritance hierarchy, which means that FooExtensions#barroom volition ne\’er beryllium referred to as (and if it had been known as, the ace would not really mention to Foo#barroom however instead to Entity#barroom which doesn’t be), since Foo#barroom volition ever beryllium recovered archetypal.

Methodology Wrapping

The large motion is: however tin we clasp connected to the barroom technique, with out really maintaining about an existent technique? The reply lies, arsenic it does truthful frequently, successful practical programming. We acquire a clasp of the methodology arsenic an existent entity, and we usage a closure (i.e. a artifact) to brand certain that we and lone we clasp connected to that entity:

people Foo def barroom 'Hullo' extremity extremity people Foo old_bar = instance_method(:barroom) define_method(:barroom) bash old_bar.hindrance(same).() + ' Planet' extremity extremity Foo.fresh.barroom # => 'Hullo Planet' 

This is precise cleanable: since old_bar is conscionable a section adaptable, it volition spell retired of range astatine the extremity of the people assemblage, and it is intolerable to entree it from anyplace, equal utilizing observation! And since Module#define_method takes a artifact, and blocks adjacent complete their surrounding lexical situation (which is wherefore we are utilizing define_method alternatively of def present), it (and lone it) volition inactive person entree to old_bar, equal last it has gone retired of range.

Abbreviated mentation:

old_bar = instance_method(:barroom) 

Present we are wrapping the barroom methodology into an UnboundMethod methodology entity and assigning it to the section adaptable old_bar. This means, we present person a manner to clasp connected to barroom equal last it has been overwritten.

old_bar.hindrance(same) 

This is a spot tough. Fundamentally, successful Ruby (and successful beautiful overmuch each azygous-dispatch based mostly OO languages), a technique is sure to a circumstantial receiver entity, known as same successful Ruby. Successful another phrases: a methodology ever is aware of what entity it was referred to as connected, it is aware of what its same is. However, we grabbed the methodology straight from a people, however does it cognize what its same is?

Fine, it doesn’t, which is wherefore we demand to hindrance our UnboundMethod to an entity archetypal, which volition instrument a Methodology entity that we tin past call. (UnboundMethods can not beryllium referred to as, due to the fact that they don’t cognize what to bash with out realizing their same.)

And what bash we hindrance it to? We merely hindrance it to ourselves, that manner it volition behave precisely similar the first barroom would person!

Lastly, we demand to call the Technique that is returned from hindrance. Successful Ruby 1.9, location is any nifty fresh syntax for that (.()), however if you are connected 1.eight, you tin merely usage the call technique; that’s what .() will get translated to anyhow.

Present are a mates of another questions, wherever any of these ideas are defined:

• However bash I mention a relation successful Ruby?
• Is Ruby’s codification artifact aforesaid arsenic C♯’s lambda look?

“Soiled” Monkey Patching

alias_method concatenation

The job we are having with our monkey patching is that once we overwrite the methodology, the methodology is gone, truthful we can not call it anymore. Truthful, fto’s conscionable brand a backup transcript!

people Foo def barroom 'Hullo' extremity extremity people Foo alias_method :old_bar, :barroom def barroom old_bar + ' Planet' extremity extremity Foo.fresh.barroom # => 'Hullo Planet' Foo.fresh.old_bar # => 'Hullo' 

The job with this is that we person present polluted the namespace with a superfluous old_bar technique. This technique volition entertainment ahead successful our documentation, it volition entertainment ahead successful codification completion successful our IDEs, it volition entertainment ahead throughout observation. Besides, it inactive tin beryllium referred to as, however presumably we monkey patched it, due to the fact that we didn’t similar its behaviour successful the archetypal spot, truthful we mightiness not privation another group to call it.

Contempt the information that this has any undesirable properties, it has unluckily go popularized done AciveSupport’s Module#alias_method_chain.

An speech: Refinements

Successful lawsuit you lone demand the antithetic behaviour successful a fewer circumstantial locations and not passim the entire scheme, you tin usage Refinements to prohibit the monkey spot to a circumstantial range. I americium going to show it present utilizing the Module#prepend illustration from supra:

people Foo def barroom 'Hullo' extremity extremity module ExtendedFoo module FooExtensions def barroom ace + ' Planet' extremity extremity refine Foo bash prepend FooExtensions extremity extremity Foo.fresh.barroom # => 'Hullo' # We haven’t activated our Refinement but! utilizing ExtendedFoo # Activate our Refinement Foo.fresh.barroom # => 'Hullo Planet' # Location it is! 

You tin seat a much blase illustration of utilizing Refinements successful this motion: However to change monkey spot for circumstantial technique?

Deserted concepts

Earlier the Ruby assemblage settled connected Module#prepend, location have been aggregate antithetic ideas floating about that you whitethorn sometimes seat referenced successful older discussions. Each of these are subsumed by Module#prepend.

Methodology Combinators

1 thought was the thought of methodology combinators from CLOS. This is fundamentally a precise light-weight interpretation of a subset of Facet-Oriented Programming.

Utilizing syntax similar

people Foo def barroom:earlier # volition ever tally earlier barroom, once barroom is referred to as extremity def barroom:last # volition ever tally last barroom, once barroom is referred to as # whitethorn oregon whitethorn not beryllium capable to entree and/oregon alteration barroom’s instrument worth extremity extremity 

you would beryllium capable to “hook into” the execution of the barroom methodology.

It is nevertheless not rather broad if and however you acquire entree to barroom’s instrument worth inside barroom:last. Possibly we may (ab)usage the ace key phrase?

people Foo def barroom 'Hullo' extremity extremity people Foo def barroom:last ace + ' Planet' extremity extremity 

Alternative

The earlier combinator is equal to prepending a mixin with an overriding methodology that calls ace astatine the precise extremity of the technique. Likewise, the last combinator is equal to prepending a mixin with an overriding methodology that calls ace astatine the precise opening of the technique.

You tin besides bash material earlier and last calling ace, you tin call ace aggregate instances, and some retrieve and manipulate ace’s instrument worth, making prepend much almighty than methodology combinators.

people Foo def barroom:earlier # volition ever tally earlier barroom, once barroom is known as extremity extremity # is the aforesaid arsenic module BarBefore def barroom # volition ever tally earlier barroom, once barroom is referred to as ace extremity extremity people Foo prepend BarBefore extremity 

and

people Foo def barroom:last # volition ever tally last barroom, once barroom is referred to as # whitethorn oregon whitethorn not beryllium capable to entree and/oregon alteration barroom’s instrument worth extremity extremity # is the aforesaid arsenic people BarAfter def barroom original_return_value = ace # volition ever tally last barroom, once barroom is known as # has entree to and tin alteration barroom’s instrument worth extremity extremity people Foo prepend BarAfter extremity 

aged key phrase

This thought provides a fresh key phrase akin to ace, which permits you to call the overwritten methodology the aforesaid manner ace lets you call the overridden technique:

people Foo def barroom 'Hullo' extremity extremity people Foo def barroom aged + ' Planet' extremity extremity Foo.fresh.barroom # => 'Hullo Planet' 

The chief job with this is that it is backwards incompatible: if you person technique referred to as aged, you volition nary longer beryllium capable to call it!

Alternative

ace successful an overriding methodology successful a prepended mixin is basically the aforesaid arsenic aged successful this message.

redef key phrase

Akin to supra, however alternatively of including a fresh key phrase for calling the overwritten technique and leaving def unsocial, we adhd a fresh key phrase for redefining strategies. This is backwards appropriate, since the syntax presently is amerciable anyhow:

people Foo def barroom 'Hullo' extremity extremity people Foo redef barroom aged + ' Planet' extremity extremity Foo.fresh.barroom # => 'Hullo Planet' 

Alternatively of including 2 fresh key phrases, we may besides redefine the which means of ace wrong redef:

people Foo def barroom 'Hullo' extremity extremity people Foo redef barroom ace + ' Planet' extremity extremity Foo.fresh.barroom # => 'Hullo Planet' 

Substitute

redefining a technique is equal to overriding the technique successful a prepended mixin. ace successful the overriding methodology behaves similar ace oregon aged successful this message.