How to resolve the algorithm Extend your language step by step in the Python programming language

Published on 12 May 2024 09:40 PM
#Python

How to resolve the algorithm Extend your language step by step in the Python programming language

Table of Contents

Problem Statement

Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements. If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch: Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following: Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large. This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be: Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Extend your language step by step in the Python programming language

The provided code is a series of conditional statements that evaluate the values of variables a and b and print different messages based on the results.

It starts by assigning the values 1 to a and 0 to b.

The following line is a conditional expression that assigns the result of the comparison a == 1 to the variable c1 and the result of the comparison b == 3 to the variable c2. This is a shorthand for writing:

c1 = a == 1
c2 = b == 3

The subsequent if-elif-else statement checks the values of c1 and c2 to determine which message to print:

  • If both c1 and c2 are True, it prints "a = 1 and b = 3".
  • If c1 is True but c2 is False, it prints "a = 1 and b <> 3".
  • If c1 is False but c2 is True, it prints "a <> 1 and b = 3".
  • If both c1 and c2 are False, it prints "a <> 1 and b <> 3".

In the provided code, the values of a and b are 1 and 0, respectively. Therefore, c1 will be True (because a == 1 is True) and c2 will be False (because b == 3 is False). As a result, the code will print "a = 1 and b <> 3".

Source code in the python programming language

a, b = 1, 0

if (c1 := a == 1) and (c2 := b == 3):
  print('a = 1 and b = 3')
elif c1:
  print('a = 1 and b <> 3')
elif c2:
  print('a <> 1 and b = 3')
else:
  print('a <> 1 and b <> 3')

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