fmtpy

A simplified input/output helper package for Go beginners, inspired by Python's simplicity.

Installation

go get github.com/grandpaej/fmtpy

Features

Basic Features

• Smart Input function with automatic type conversion
• Print function supporting both Go-style and Python-style formatting
• Modular package structure for clean imports
• Color functions that work seamlessly with fmt.Print, fmt.Println, fmt.Printf
• Comprehensive string manipulation functions
• No performance loss compared to standard fmt package
• Beginner-friendly API

Package Structure

import (
    "github.com/grandpaej/fmtpy"        // Core input/output
    "github.com/grandpaej/fmtpy/color" // Color functions
    "github.com/grandpaej/fmtpy/input" // String manipulation
)

Smart Input with Type Conversion

The new Input() function returns an InputValue that can be converted to any type:

package main

import (
    "fmt"
    "github.com/grandpaej/fmtpy"
)

func main() {
    // Direct type conversion - exactly what you wanted!
    var age int
    age = fmtpy.Input("Enter your age: ").Int()

    var score float64
    score = fmtpy.Input("Enter your score: ").Float()

    name := fmtpy.Input("Enter your name: ").String()
    confirmed := fmtpy.Input("Confirm (y/n): ").Bool()

    fmt.Printf("Name: %s, Age: %d, Score: %.2f, Confirmed: %t\n",
               name, age, score, confirmed)
}

Colors That Work with fmt

package main

import (
    "fmt"
    "github.com/grandpaej/fmtpy/color"
)

func main() {
    // Works with any type and any fmt function!
    fmt.Println(color.Red("Error message"))
    fmt.Println(color.Green(42))           // Numbers
    fmt.Println(color.Blue(1+1))           // Expressions
    fmt.Printf("Result: %s\n", color.Yellow(123.45))

    // Bold colors
    fmt.Println(color.BoldRed("Important!"))
    fmt.Println(color.BoldGreen("Success!"))

    // Background colors
    fmt.Println(color.OnYellow("Warning"))
    fmt.Println(color.OnRed("Critical"))
}

Color Support

package main

import (
    "fmt"
    "github.com/grandpaej/fmtpy/color"
)

func main() {
    c := color.Get()
    
    // Basic colors - Short form
    fmt.Println(c.R("Red text"))
    fmt.Println(c.G("Green text"))
    fmt.Println(c.B("Blue text"))
    
    // Bold colors
    fmt.Println(c.BR("Bold red"))
    fmt.Println(c.BG("Bold green"))
    
    // Background colors
    fmt.Println(c.OnR("Red background"))
    fmt.Println(c.OnY("Yellow background"))
    
    // Semantic styles
    fmt.Println(c.E("This is an error"))
    fmt.Println(c.S("This is a success"))
    fmt.Println(c.I("This is info"))
    fmt.Println(c.W("This is a warning"))
    
    // With formatting
    name := "World"
    fmt.Println(c.S("Hello, {n}!", name))
}

Available Color Methods

Short Form Colors

• R() - Red text
• G() - Green text
• B() - Blue text
• Y() - Yellow text
• M() - Magenta text
• C() - Cyan text

Bold Colors

• BR() - Bold red
• BG() - Bold green
• BB() - Bold blue
• BY() - Bold yellow
• BM() - Bold magenta
• BC() - Bold cyan

Background Colors

• OnR() - Red background
• OnG() - Green background
• OnB() - Blue background
• OnY() - Yellow background
• OnM() - Magenta background
• OnC() - Cyan background

Semantic Helpers

• E() - Error (Red)
• S() - Success (Green)
• I() - Info (Blue)
• W() - Warning (Yellow)

Type-Specific Input

• InputInt(prompt) - Get integer input
• InputFloat(prompt) - Get float input
• Ask(prompt) - Get yes/no input (returns bool)

String Manipulation Functions

Case Conversion

• Upper(s) - Convert to uppercase
• Lower(s) - Convert to lowercase
• Title(s) - Convert to title case (first letter of each word)
• Capitalize(s) - Capitalize first letter, lowercase the rest
• SwapCase(s) - Swap case of all letters

String Operations

• Reverse(s) - Reverse a string
• Repeat(s, n) - Repeat string n times
• Replace(s, old, new) - Replace all occurrences
• Split(s, sep) - Split string by separator
• Join(parts, sep) - Join string slice with separator
• Trim(s) - Remove leading/trailing whitespace

String Analysis

• Contains(s, substring) - Check if string contains substring
• StartsWith(s, prefix) - Check if string starts with prefix
• EndsWith(s, suffix) - Check if string ends with suffix
• Length(s) - Get character count (Unicode-aware)
• WordCount(s) - Count words in string
• CharCount(s) - Count characters in string
• Count(s, substring) - Count occurrences of substring

String Extraction

• Substring(s, start, end) - Extract substring
• FirstWord(s) - Get first word
• LastWord(s) - Get last word
• Lines(s) - Split into lines
• Words(s) - Split into words

String Filtering

• OnlyLetters(s) - Keep only alphabetic characters
• OnlyNumbers(s) - Keep only numeric characters
• RemoveSpaces(s) - Remove all spaces

String Validation

• IsEmpty(s) - Check if empty or whitespace only
• IsNumber(s) - Check if string is a valid number
• IsLetter(s) - Check if string contains only letters

Type Conversion

• ToInt(s) - Convert to int (returns 0 if invalid)
• ToFloat(s) - Convert to float64 (returns 0.0 if invalid)
• ToString(v) - Convert any value to string

String Formatting

• Center(s, width) - Center string within width
• LeftPad(s, width, char) - Pad left with character
• RightPad(s, width, char) - Pad right with character

String Manipulation Examples

package main

import (
    "fmt"
    "github.com/grandpaej/fmtpy"
    "github.com/grandpaej/fmtpy/input"
)

func main() {
    text := "Hello World"

    // Case conversion
    fmt.Println(input.Upper(text))      // "HELLO WORLD"
    fmt.Println(input.Lower(text))      // "hello world"
    fmt.Println(input.Title(text))      // "Hello World"
    fmt.Println(input.SwapCase(text))   // "hELLO wORLD"

    // String operations
    fmt.Println(input.Reverse(text))    // "dlroW olleH"
    fmt.Println(input.Repeat("Hi", 3))  // "HiHiHi"

    // Analysis
    fmt.Println(input.WordCount(text))  // 2
    fmt.Println(input.Length(text))     // 11
    fmt.Println(input.FirstWord(text))  // "Hello"

    // Filtering
    mixed := "Hello123World"
    fmt.Println(input.OnlyLetters(mixed))  // "HelloWorld"
    fmt.Println(input.OnlyNumbers(mixed))  // "123"

    // Formatting
    fmt.Println(input.Center("Hi", 10))           // "    Hi    "
    fmt.Println(input.LeftPad("Hi", 5, "*"))     // "***Hi"
    fmt.Println(input.RightPad("Hi", 5, "-"))    // "Hi---"

    // Smart input with type conversion
    var age int = fmtpy.Input("Enter your age: ").Int()
    var score float64 = fmtpy.Input("Enter your score: ").Float()

    // Yes/no questions
    if fmtpy.Input("Do you like Go? (y/n): ").Bool() {
        fmt.Println("Great choice!")
    }
}

Complete Example

package main

import (
    "fmt"
    "github.com/grandpaej/fmtpy"
    "github.com/grandpaej/fmtpy/color"
    "github.com/grandpaej/fmtpy/input"
)

func main() {
    // Get user input with automatic type conversion
    name := fmtpy.Input("What's your name? ").String()
    var age int = fmtpy.Input("How old are you? ").Int()
    var score float64 = fmtpy.Input("Enter your score: ").Float()

    // Use colors with fmt functions
    fmt.Println(color.Green("=== User Profile ==="))
    fmt.Printf("Name: %s\n", color.Blue(name))
    fmt.Printf("Age: %s\n", color.Cyan(age))
    fmt.Printf("Score: %s\n", color.Yellow(score))

    // String manipulation
    fmt.Printf("Name in uppercase: %s\n", color.BoldRed(input.Upper(name)))
    fmt.Printf("Reversed name: %s\n", color.Magenta(input.Reverse(name)))

    // Combine everything
    if fmtpy.Input("Save profile? (y/n): ").Bool() {
        fmt.Println(color.BoldGreen("✅ Profile saved successfully!"))
    } else {
        fmt.Println(color.BoldYellow("⚠️  Profile not saved"))
    }
}

📚 Examples

The example/ directory contains comprehensive examples:

• basic_usage.go - Simple input, colors, and string manipulation
• advanced_features.go - Text processing, validation, and interactive menus
• color_showcase.go - Complete color demonstration with fmt functions
• string_manipulation.go - All string manipulation features
• main.go - Complete feature demonstration

Run any example:

cd example
go run basic_usage.go
go run color_showcase.go

🎯 Quick Reference

Input with Type Conversion

// The new way - exactly what you wanted!
var age int = fmtpy.Input("Age: ").Int()
var score float64 = fmtpy.Input("Score: ").Float()
name := fmtpy.Input("Name: ").String()
confirmed := fmtpy.Input("Confirm (y/n): ").Bool()

Colors (work with any fmt function)

fmt.Println(color.Red("Error"))           // Basic colors
fmt.Println(color.BoldGreen("Success"))   // Bold colors
fmt.Println(color.OnYellow("Warning"))    // Background colors
fmt.Printf("Number: %s\n", color.Cyan(42)) // Any data type

String Manipulation

input.Upper("hello")           // "HELLO"
input.Reverse("hello")         // "olleh"
input.WordCount("hello world") // 2
input.OnlyNumbers("abc123")    // "123"
input.Center("hi", 10)         // "    hi    "

📖 Complete API Reference

Core Package (fmtpy)

Input Functions

• Input(prompt) InputValue - Smart input with type conversion
• Print(format, args...) - Enhanced print with Python f-string support

InputValue Methods

• .String() - Convert to string
• .Int() - Convert to int (returns 0 if invalid)
• .Float() - Convert to float64 (returns 0.0 if invalid)
• .Bool() - Convert to bool (y/yes/true/1 = true)

Color Package (fmtpy/color)

Basic Colors

• Red(v), Green(v), Blue(v), Yellow(v), Magenta(v), Cyan(v), White(v), Black(v)

Bold Colors

• BoldRed(v), BoldGreen(v), BoldBlue(v), BoldYellow(v), BoldMagenta(v), BoldCyan(v)

Background Colors

• OnRed(v), OnGreen(v), OnBlue(v), OnYellow(v), OnMagenta(v), OnCyan(v)

All color functions accept any data type and work with fmt.Print, fmt.Println, fmt.Printf

Input Package (fmtpy/input)

Case Conversion

• Upper(s) - Convert to UPPERCASE
• Lower(s) - Convert to lowercase
• Title(s) - Convert To Title Case
• Capitalize(s) - Capitalize first letter only
• SwapCase(s) - sWAP cASE

String Operations

• Reverse(s) - Reverse string
• Repeat(s, n) - Repeat string n times
• Replace(s, old, new) - Replace all occurrences
• Split(s, sep) - Split by separator
• Join(parts, sep) - Join with separator
• Trim(s) - Remove leading/trailing whitespace

String Analysis

• Contains(s, sub) - Check if contains substring
• StartsWith(s, prefix) - Check if starts with prefix
• EndsWith(s, suffix) - Check if ends with suffix
• Length(s) - Character count (Unicode-aware)
• WordCount(s) - Count words
• CharCount(s) - Count characters
• Count(s, sub) - Count occurrences of substring

String Extraction

• Substring(s, start, end) - Extract substring
• FirstWord(s) - Get first word
• LastWord(s) - Get last word
• Lines(s) - Split into lines
• Words(s) - Split into words

String Filtering

• OnlyLetters(s) - Keep only alphabetic characters
• OnlyNumbers(s) - Keep only numeric characters
• RemoveSpaces(s) - Remove all spaces

String Validation

• IsEmpty(s) - Check if empty or whitespace only
• IsNumber(s) - Check if valid number
• IsLetter(s) - Check if contains only letters

Type Conversion

• ToInt(s) - Convert to int (returns 0 if invalid)
• ToFloat(s) - Convert to float64 (returns 0.0 if invalid)
• ToString(v) - Convert any value to string

String Formatting

• Center(s, width) - Center string within width
• LeftPad(s, width, char) - Pad left with character
• RightPad(s, width, char) - Pad right with character

🚀 Migration Guide

From Old fmtpy

// Old way
name := fmtpy.Input("Name: ")
age := fmtpy.InputInt("Age: ")

// New way (recommended)
name := fmtpy.Input("Name: ").String()
var age int = fmtpy.Input("Age: ").Int()

From Standard Go

// Standard Go
var age int
fmt.Print("Enter age: ")
fmt.Scanf("%d", &age)

// fmtpy way
var age int = fmtpy.Input("Enter age: ").Int()

🎨 Advanced Color Usage

Custom Color Combinations

// Legacy color functions (still supported)
fmt.Println(color.RedText("Red text with {placeholder}", "value"))
fmt.Println(color.BoldRedText("Bold red text"))

// New simple functions (recommended)
fmt.Println(color.Red("Simple red text"))
fmt.Println(color.BoldRed("Bold red text"))

Color with Complex Data

// Colors work with any data type
users := []string{"Alice", "Bob", "Charlie"}
fmt.Printf("Users: %s\n", color.Green(users))

result := map[string]int{"score": 95, "level": 5}
fmt.Printf("Result: %s\n", color.Blue(result))

🔧 Performance Notes

• Zero speed abuse: All functions are optimized for performance
• Memory efficient: No unnecessary allocations
• Unicode support: Proper handling of international characters
• Safe conversions: Type conversions never panic, return sensible defaults

🌍 Environment Variables

• NO_COLOR: Set this to disable colors
• TERM=dumb: Colors will be disabled automatically

🤝 Contributing

Feel free to open issues or submit pull requests!

Development Setup

git clone https://github.com/grandpaej/fmtpy
cd fmtpy
go test ./...

📄 License

MIT License

🎯 Why fmtpy?

• Beginner-friendly: Simple, intuitive API
• Type-safe: Smart input conversion without panics
• Modular: Import only what you need
• Compatible: Works with standard fmt functions
• Colorful: Rich color support for better UX
• Fast: Zero performance overhead
• Unicode: Proper international character support

Perfect for:

• 🎓 Learning Go programming
• 🛠️ Building CLI tools
• 📊 Creating interactive programs
• 🎨 Adding colors to terminal output
• ⚡ Rapid prototyping