This page provides some hints for using Pharo's numbers. For more detailled information, check Pharo by Example book.
As written in Pharo by Example book,
Remarkably, numbers in Smalltalk are not primitive data values but true objects. Of course numbers are implemented efficiently in the virtual machine, but the Number hierarchy is as perfectly accessible and extensible as any other portion of the Smalltalk class hierarchy. - Pharo by Example, Chapter 8 Section 2
Which is an interesting feature because it means that extension methods can be added to create objects holding a quantity. This is what is done for Durations:
5 seconds. "0:00:00:05"#seconds method creates a new instance of Duration representing the number second required.
Scaled decimals allow one to model rationals. That is to say numbers with a fixed number of decimals. They are handy when dealing with money for example. It is possible to create a ScaledDecimal from its litteral form using the s notation: 1.45s2 which will store 1.45 with 2 digits precision in decimals.
- Infinity:
Float infinity - Negative infinity:
Float negativeInfinity - Not a number:
Float nan - Pi, 2*Pi, 3*Pi:
Float pi. Float twoPi. Float threePi - Euler's number:
Float e
The class-side methods #readFrom: and #readFrom:base: of Number class allow one to parse a number from a String. Here are some examples:
Number readFrom: '10'. "10"
Number readFrom: '10' base: 2. "2"
Number readFrom: '1.0'. "1.0"A specific subclass of Number can be used to ensure that the object created by the parser is of a specific kind:
Integer readFrom: '10'. "10"
Float readFrom: '1.0'. "1.0"