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* Implement minmax for Range; Simplify range command * Port random integer to enginep; New FromValue impl Now, FromValue is implemented for Tagged<Range> to allow extracting args into this type. * Make sure range value extraction fails properly The range endpoint extraction methods now return error instead of silently clipping the value. This now makes `random integer ..-4` fail properly since -4 can't be cast as u64. * Port random decimal to enginep & Refactor This added a way to interpret Range limits as f64 and a Primitive helper to get its value as f64. A side effect of this commit is that it is now possible to specify the command bounds as true decimals. E.g., `random decimal 0.0..3.14` does not clip 3.14 to 3. |
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Nu-Engine
Nu-engine handles most of the core logic of nushell. For example, engine handles: - Passing of data between commands - Evaluating a commands return values - Loading of user configurations
Top level introduction
The following topics shall give the reader a top level understanding how various topics are handled in nushell.
How are environment variables handled?
Environment variables (or short envs) are stored in the Scope of the EvaluationContext. That means that environment variables are scoped by default and we don't use std::env to store envs (but make exceptions where convenient).
Nushell handles environment variables and their lifetime the following:
- At startup all existing environment variables are read and put into
Scope. (Nushell reads existing environment variables platform independent by asking theHost. They will most likely come fromstd::env::*) - Envs can also be loaded from config files. Each loaded config produces a new
ScopeFramewith the envs of the loaded config. - Nu-Script files and internal commands read and write env variables from / to the
Scope. External scripts and binaries can't interact with theScope. Therefore all env variables are read from theScopeand put into the external binaries environment-variables-memory area.