Questions tagged [design-patterns]

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How do I erase the “shadow-world” antipattern?

In this antipattern, you have level-0 constructs of the language, which are then abstracted over by creating level-1 constructions, and these level-1 abstractions are abstracted over by creating level-...
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29 views

What are the pros and cons of these two coding patterns/structures? And do they have a formal term?

I have traditionally been doing things like this: function test() // A { if (/* conditions */) return true; else return false; } Of late, ...
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27 views

Finite state machine for a modified traffic controller

Consider a traffic light controller for an intersection of a main street and a smaller street. Both streets are one-way streets. The intersection has two traffic lights, one for each street. In normal ...
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1answer
26 views

How does this example violate Liskov substitution principle, which then causes violation of the open-closed principle?

From Agile Principles, Patterns, and Practices in C# by Robert Martin, Listing 10-1. A violation of LSP causing a violation of OCP ...
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1answer
34 views

design cache system using queuing theory

If we have data from a random population, a 3d histogram of throughput and current cache size of DRAM (intersection of a IOPS & a cache size will have a count). How can one use queuing theory to ...
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14 views

What is the difference between a composite and a leaf in a composite pattern?

I think the initial is sometimes called a compositor. Essentially from the diagrams of what I have seen so far from the design pattern is that compositors are more complex in its attributes while the ...
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0answers
32 views

Building an architecture without pointers, objects, memory allocation or first class functions [closed]

Many sources for good software architecture will use objects, pointers, memory allocation in their solutions. The PLC programming language 61131-3 Structured Text is really limited in this regard, ...
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1answer
36 views

State Machine and State transition Table - Explanation and Creation Of

How do I create a state transition table/array in actual code/pseudo-code? I haven't experienced the "ah-ha" moment yet with the state machine to coding (and I really want to). I've looked at several ...
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1answer
106 views

What is the difference between a “meta model” and “design patterns”?

Where is the difference between a "meta model" and "design patterns"? If you take, for example, Fowlers "Identity Field" from his book "Patterns Of Enterprise Application Architecture": Why is this a ...
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1answer
971 views

Is there a way of objectively measuring the efficiency or quality of software or code design?

I've been thinking about ways of measuring code, and, quite frankly, I can't think of truly objective, semi-universal ways of evaluating the quality or "strength" of code to say, "Yes, this is better ...
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3answers
505 views

Design patterns for simple text based scripting language?

In my current application I am trying to determine the best way to implement a simple scripting language. This language would allow a user to create a script that controls a machine with various ...
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2answers
43 views

Is there a formal term for functions that have static state across executions?

Two examples, one in PHP: function adder($i){ static $a = 0; $a += $i; return $a; } A similar effect can be achieved with closures in javascript: ...
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218 views

What's the difference between declarative syntax and encapsulation?

I had been first introduced to the idea of declarative syntax when using Angular JS. From what I understand, the idea is that you say, "do this" instead of "in order to do this, do this, this and this"...
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2k views

Combine abstract factory with decorator pattern [closed]

I'm working on a simple project of software engineering that should combine two patterns. I choose Abstract Factory and Decorator patterns to modify (dynamically) objects created with the concrete ...