🚫 WhyNotPackage

Explains why a specific version of a package cannot be installed. Equivalent to composer why-not package/name version.

When to use

• 🐛 When you hit a conflict while upgrading or pinning a version and need to locate which constraint blocks the installation.
• 🔍 To evaluate whether a specific version can be introduced.
• 📋 To explain the root cause of a version choice in a dependency review.

Signature

func (c *Composer) WhyNotPackage(packageName string, version string) (string, error)

Parameters

Parameter	Type	Description
packageName	string	Name of the package to query
version	string	Version to query, e.g. v4.0.0

Return value

Value	Type	Description
Output	string	Output of the explanation, listing the chain of constraints that block the installation
Error	error	Returned when an error occurs during the query

Example

package main

import (
    "fmt"
    "log"

    "github.com/scagogogo/composer-skills/pkg/composer"
)

func main() {
    comp, err := composer.New(composer.DefaultOptions())
    if err != nil {
        log.Fatalf("init failed: %v", err)
    }

    output, err := comp.WhyNotPackage("symfony/console", "v4.0.0")
    if err != nil {
        log.Fatalf("query version constraint failed: %v", err)
    }
    fmt.Println("reason it cannot be installed:", output)
}

Advanced

WhyNotWithOptions

Use this when you need to pass additional options (additional_methods.go):

func (c *Composer) WhyNotWithOptions(packageName, version string, options map[string]string) (string, error)

Forward question

• To find out "why a package is installed", use WhyPackage.
• To find out "whether you can upgrade to the latest", use OutdatedPackages or the structured GetOutdatedInfo.

Version format

version should be a version string Composer can recognize, such as v4.0.0, ^4.0, etc. Passing an invalid format may produce error output that is hard to interpret.

🔍 Related methods

• WhyPackage: explain why a package is installed.
• OutdatedPackages: view upgradeable packages.