Questions tagged [design-patterns]

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Questions on a Python Creational Design Pattern

I came across a potential creational design pattern when programming in Python that I haven't seen before and I wanted to get some opinions on whether it is advisable to use this approach. Problem: ...
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2answers
67 views

Is there one (or a few) canonical/ specific use cases for "functions returning functions" (beyond "decorators")?

Is there one (or a few) canonical/ specific use cases for "functions returning functions" (beyond "decorators")? What can you do with "functions returning functions" ...
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27 views

system architecture or software architecture

I was trying to get started with a small project but I quickly realized I had to do more research on the subject. Suppose, when creating a site, in production, there's a certain structure how the ...
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14 views

When to dynamically compute data vs. when to use variables and update on demand?

Two scenarios: Function is called and data is computed and returned. Data is saved in variable, updated when required, data is retrieved from variable. So I was wondering in what kind of scenarios ...
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25 views

What would be be a nice design pattern to code a function that implements a math function but doesn't know which parts of the equation get passed?

Take for example the Pythagorean theorem: a^2 + b^2 = c^2. This example is a little simple so please conside a function with 7 variables that are related. I would like to design the function in a way ...
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11 views

Best way to code a shopping cart consisting of items with different properties

This is an interview question. Interviewer wanted a scalable solution Goal is to find value of shopping cart. Cart could have 3 different types of items(Physical,Digital,URL). Only Physical Items have ...
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30 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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1answer
71 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
45 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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0answers
53 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
72 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
149 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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3answers
743 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 ...
6
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1answer
1k 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 ...
3
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2answers
44 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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2answers
266 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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1answer
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 ...