Why brew needs python while installing php7

Question

While installing php via brew on MacOs, i got the output below. So i am asking why python dependency is needed while installing php?

==> Installing dependencies for [email protected]: [email protected] and glib
==> Installing [email protected] dependency: [email protected]
==> Pouring [email protected]_4.mojave.bottle.tar.gz
==> /usr/local/Cellar/[email protected]/3.9.1_4/bin/python3 -m ensurepip
==> /usr/local/Cellar/[email protected]/3.9.1_4/bin/pip3 install -v --global-option=--no-user-cfg --install-option=--force --install-option=--single-version-externally-managed --install-option=--record=installed.txt --upgrade --target=/usr/local
==> Caveats
Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/[email protected]/libexec/bin

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /usr/local/lib/python3.9/site-packages

See: https://docs.brew.sh/Homebrew-and-Python
==> Summary
🍺  /usr/local/Cellar/[email protected]/3.9.1_4: 3,932 files, 61.7MB
==> Installing [email protected] dependency: glib
==> Pouring glib-2.66.4_1.mojave.bottle.1.tar.gz
==> Caveats
Bash completion has been installed to:
  /usr/local/etc/bash_completion.d
==> Summary
🍺  /usr/local/Cellar/glib/2.66.4_1: 441 files, 20.3MB
==> Installing [email protected]

Answer 1

I know this question has some age but I just want to answer it.

---

In Homebrew, [email protected] depends on [email protected], it is because:

1. [email protected] does NOT depend on [email protected]. See the output of brew deps --tree [email protected] below
2. Homebrew requires Python (and it will update the version from time to time) in some cases (read this), as it does not use the system Python version.

Conclusion: it's Homebrew that needs Python, not PHP 7.4.

Output of brew deps --tree [email protected]:

[email protected]
├── apr
├── apr-util
│   ├── apr
│   └── openssl@3
│       └── ca-certificates
├── argon2
├── aspell
├── autoconf
│   └── m4
├── curl
│   ├── brotli
│   ├── libidn2
│   │   ├── libunistring
│   │   └── gettext
│   ├── libnghttp2
│   ├── libssh2
│   │   └── openssl@3
│   │       └── ca-certificates
│   ├── openldap
│   │   └── openssl@3
│   │       └── ca-certificates
│   ├── openssl@3
│   │   └── ca-certificates
│   ├── rtmpdump
│   │   └── openssl@3
│   │       └── ca-certificates
│   └── zstd
│       ├── lz4
│       └── xz
├── freetds
│   ├── openssl@3
│   │   └── ca-certificates
│   └── unixodbc
│       └── libtool
│           └── m4
├── gd
│   ├── fontconfig
│   │   └── freetype
│   │       └── libpng
│   ├── freetype
│   │   └── libpng
│   ├── jpeg-turbo
│   ├── libavif
│   │   ├── aom
│   │   │   ├── jpeg-xl
│   │   │   │   ├── brotli
│   │   │   │   ├── giflib
│   │   │   │   ├── highway
│   │   │   │   ├── imath
│   │   │   │   ├── jpeg-turbo
│   │   │   │   ├── libpng
│   │   │   │   ├── little-cms2
│   │   │   │   │   ├── jpeg-turbo
│   │   │   │   │   └── libtiff
│   │   │   │   │       ├── jpeg-turbo
│   │   │   │   │       ├── xz
│   │   │   │   │       └── zstd
│   │   │   │   │           ├── lz4
│   │   │   │   │           └── xz
│   │   │   │   ├── openexr
│   │   │   │   │   └── imath
│   │   │   │   └── webp
│   │   │   │       ├── giflib
│   │   │   │       ├── jpeg-turbo
│   │   │   │       ├── libpng
│   │   │   │       └── libtiff
│   │   │   │           ├── jpeg-turbo
│   │   │   │           ├── xz
│   │   │   │           └── zstd
│   │   │   │               ├── lz4
│   │   │   │               └── xz
│   │   │   └── libvmaf
│   │   ├── jpeg-turbo
│   │   └── libpng
│   ├── libpng
│   ├── libtiff
│   │   ├── jpeg-turbo
│   │   ├── xz
│   │   └── zstd
│   │       ├── lz4
│   │       └── xz
│   └── webp
│       ├── giflib
│       ├── jpeg-turbo
│       ├── libpng
│       └── libtiff
│           ├── jpeg-turbo
│           ├── xz
│           └── zstd
│               ├── lz4
│               └── xz
├── gettext
├── gmp
├── icu4c
├── krb5
│   └── openssl@3
│       └── ca-certificates
├── libpq
│   ├── krb5
│   │   └── openssl@3
│   │       └── ca-certificates
│   └── openssl@3
│       └── ca-certificates
├── libsodium
├── libzip
│   └── zstd
│       ├── lz4
│       └── xz
├── oniguruma
├── openldap
│   └── openssl@3
│       └── ca-certificates
├── [email protected]
│   └── ca-certificates
├── pcre2
├── sqlite
│   └── readline
├── tidy-html5
└── unixodbc
    └── libtool
        └── m4

Or if you prefer a graphical version that shows in a browser, you can use this command:

brew deps --graph [email protected]

Last, if you only prefer a summary of all dependencies, you can use this command:

brew deps [email protected]