Expressions improvements: escape chars and unicode #1333
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
If variables have names which include symbols like + then expressions need to escape the symbols to avoid treating them as arithmetic operators. This can be important when evolving variables with names like "H+" or "He+2". Two mechanisms currently allowed: 1. A backslash (\) escapes the following character, so an expression could include something like "h2\+:density" as a symbol 2. Backquotes escape a sequence of characters, so "`h2+:density`" or "h`2+`:density" could be used. Note that the colon symbol always indicates section, and is not escaped. This is to avoid ambiguity. The options reader therefore checks if keys include `:` and throws if they do. Unit tests added for all these things
To be continued...
Describes how to use variables with symbols in expressions by escaping them using \ or ` methods.
Symbols in expressions can now have a much wider range of characters, including utf-8. Anything except whitespace and some reserved operators and brackets, which can be escaped if needed. Updated documentation, added tests.
Was being included in the symbol, so functions of two arguments failed. A unit test is added to catch this. Updated documentation
If a number is followed by a symbol or an opening bracket, then a multiplication is assumed. This is a nice (I think) feature of Julia which reduces clutter in large expressions. `3sin(2π*x)` or `3 sin(2 π * x)` are equivalent to `3*sin(2*π*x)`. Added tests and documentation.
bendudson
changed the title
ZedThree
approved these changes
Oct 22, 2018
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
New features:
Includes unit tests and documentation
Escaping characters
If variables have names which include symbols like + then expressions need to escape the symbols to avoid treating them as arithmetic operators. This can be important when evolving variables with names
like "H+" or "He+2".
Two mechanisms currently allowed:
A backslash () escapes the following character, so an expression could include something like "h2+:density" as a symbol
Backquotes escape a sequence of characters, so "
h2+:density" or "h2+:density" could be used.Note that the colon symbol always indicates section, and is not escaped. This is to avoid ambiguity. The options reader therefore checks if keys include
:and throws if they do.Unicode names
The reader has been made less strict about what it accepts as a valid symbol. Rules are:
:(as reserved for sections).(or it will be read as a number). These can be escaped.When referred to in an expression, arithmetic operators, brackets, commas (
+-*/^(){}[],) and whitespace must be escaped.Implicit multiplication
If a number is followed by a symbol or an opening bracket, then a multiplication is assumed. This is a nice (I think) feature of Julia which reduces clutter in expressions.
3sin(2π*x)or3 sin(2 π * x)are equivalent to3*sin(2*pi*x).