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73 lines
2.3 KiB
Markdown
73 lines
2.3 KiB
Markdown
# Managing dependencies
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## Concepts
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- Deno uses URLs for dependency management.
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- One convention places all these dependent URLs into a local `deps.ts` file.
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Functionality is then exported out of `deps.ts` for use by local modules.
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- Continuing this convention, dev only dependencies can be kept in a
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`dev_deps.ts` file.
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- See also [Linking to external code](../linking_to_external_code.md)
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## Overview
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In Deno there is no concept of a package manager as external modules are
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imported directly into local modules. This raises the question of how to manage
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remote dependencies without a package manager. In big projects with many
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dependencies it will become cumbersome and time consuming to update modules if
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they are all imported individually into individual modules.
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The standard practice for solving this problem in Deno is to create a `deps.ts`
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file. All required remote dependencies are referenced in this file and the
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required methods and classes are re-exported. The dependent local modules then
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reference the `deps.ts` rather than the remote dependencies. If now for example
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one remote dependency is used in several files, upgrading to a new version of
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this remote dependency is much simpler as this can be done just within
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`deps.ts`.
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With all dependencies centralized in `deps.ts`, managing these becomes easier.
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Dev dependencies can also be managed in a separate `dev_deps.ts` file, allowing
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clean separation between dev only and production dependencies.
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## Example
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```ts
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/**
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* deps.ts
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*
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* This module re-exports the required methods from the dependant remote Ramda module.
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**/
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export {
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add,
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multiply,
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} from "https://x.nest.land/ramda@0.27.0/source/index.js";
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```
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In this example the same functionality is created as is the case in the
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[local and remote import examples](./import_export.md). But in this case instead
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of the Ramda module being referenced directly it is referenced by proxy using a
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local `deps.ts` module.
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**Command:** `deno run example.ts`
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```ts
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/**
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* example.ts
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*/
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import { add, multiply } from "./deps.ts";
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function totalCost(outbound: number, inbound: number, tax: number): number {
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return multiply(add(outbound, inbound), tax);
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}
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console.log(totalCost(19, 31, 1.2));
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console.log(totalCost(45, 27, 1.15));
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/**
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* Output
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*
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* 60
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* 82.8
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*/
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```
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