std/envvars

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The std/envvars module implements environment variable handling.

Imports

oserrors, win_setenv, winlean

Types

ReadEnvEffect = object of ReadIOEffect

Effect that denotes a read from an environment variable. Source Edit

WriteEnvEffect = object of WriteIOEffect

Effect that denotes a write to an environment variable. Source Edit

Procs

proc delEnv(key: string) {....tags: [WriteEnvEffect], raises: [OSError],
                           forbids: [].}

Deletes the environment variable named key. If an error occurs, OSError is raised.

See also:ven

• getEnv proc
• existsEnv proc
• putEnv proc
• envPairs iterator

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proc existsEnv(key: string): bool {....tags: [ReadEnvEffect], raises: [],
                                    forbids: [].}

Checks whether the environment variable named key exists. Returns true if it exists, false otherwise.

See also:

• getEnv proc
• putEnv proc
• delEnv proc
• envPairs iterator

Example:

assert not existsEnv("unknownEnv")

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proc getEnv(key: string; default = ""): string {....tags: [ReadEnvEffect],
    raises: [], forbids: [].}

Returns the value of the environment variable named key.

If the variable does not exist, "" is returned. To distinguish whether a variable exists or it's value is just "", call existsEnv(key) proc.

See also:

• existsEnv proc
• putEnv proc
• delEnv proc
• envPairs iterator

Example:

assert getEnv("unknownEnv") == ""
assert getEnv("unknownEnv", "doesn't exist") == "doesn't exist"

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proc putEnv(key, val: string) {....tags: [WriteEnvEffect], raises: [OSError],
                                forbids: [].}

Sets the value of the environment variable named key to val. If an error occurs, OSError is raised.

See also:

• getEnv proc
• existsEnv proc
• delEnv proc
• envPairs iterator

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Iterators

iterator envPairs(): tuple[key, value: string] {....tags: [ReadEnvEffect],
    raises: [], forbids: [].}

Iterate over all environments variables.

In the first component of the tuple is the name of the current variable stored, in the second its value.

Works in native backends, nodejs and vm, like the following APIs:

• getEnv proc
• existsEnv proc
• putEnv proc
• delEnv proc

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