Storing and Injecting Reusable Style Patterns
FSCSS introduces a powerful paradigm for managing stylesheets: Style Replacement. This mechanism allows developers to define, store, and dynamically inject reusable blocks of CSS, ensuring consistency, reducing redundancy, and simplifying maintenance across your web components. It's akin to creating highly efficient, named CSS "snippets" that you can drop into any selector.
At its core, Style Replacement in FSCSS leverages three key functional methods: str(), re(), and the underlying store() mechanism (which is implicitly managed by str()).
Core FSCSS Functional Methods for Style Replacement
-
str(name, styles): Storing Style Patterns
- Purpose: This is the primary method for defining a reusable block of CSS. You assign a unique name to a set of styles (CSS declarations).
- Mechanism: When the FSCSS preprocessor encounters a str() declaration, it parses the styles string and registers it in its internal style store() under the provided name. This effectively creates a named reference to that specific CSS pattern.
- Syntax: str(myPatternName, " property-one: value; property-two: value; /* ... more CSS declarations ... */ ")
- Benefit: Centralizes common design elements. Instead of repeating the same padding, border-radius, shadow, and background for every "card-like" component, you define them once.
-
re(name): Recalling and Injecting Stored Styles (Direct Injection)
- Purpose: While re() is mentioned, your example implies a more direct, implicit injection for simple name lookups. If re() is explicitly available, it would be used to retrieve the stored CSS content for more complex scenarios, potentially involving dynamic naming or more advanced pattern matching. However, for direct style replacement as shown in your example, FSCSS allows you to simply use the name of the stored pattern directly within a selector block.
- Mechanism (Implicit re()): When the FSCSS preprocessor encounters a previously str()-ed name (e.g., cardStyle) within a CSS rule's declaration block, it performs a textual substitution. It looks up the name in its store() and replaces the name with the full CSS block associated with it. This is similar to how a mixin is "included" in other preprocessors.
- Syntax (Implicit Injection): .my-component { myPatternName; /* FSCSS replaces 'myPatternName' with its stored styles / / ... component-specific styles ... */ }
- Benefit:
- Reduces Code Duplication: You write the common styles once and reference them multiple times.
- Ensures Consistency: Every element where cardStyle is injected will have the exact same base visual properties, enforcing design system rules.
- Enhances Readability: CSS rules become cleaner and more focused on their unique attributes, with shared styles abstracted away.
- Simplifies Maintenance: A single change to a str() definition propagates across your entire stylesheet, updating all instances where that pattern is used. This is invaluable for global style updates or refactoring.
-
store(): The Internal Style Repository (Implicit)
- Purpose: This isn't a method you directly call to add styles in the same way str() is. Instead, store() refers to the internal data structure or registry within the FSCSS preprocessor where all str()-defined style patterns are held.
- Mechanism: str() operations add definitions to this internal store(). When FSCSS encounters a name during processing, it queries this store() to retrieve the corresponding CSS.
- Benefit: Provides the underlying infrastructure for str() and re() to function, acting as the central "database" for your reusable style patterns. When to Leverage Style Replacement in FSCSS
Establishing Design System Components: Define base styles for common UI elements like buttons, cards, forms, and alerts, making them readily available and consistent.
Applying Theming: Create different str() patterns for dark mode, light mode, or brand variations, and conditionally inject them.
Standardizing Layouts: Encapsulate common flexbox or grid patterns that are reused across different sections or components.
Managing Complex Visual Effects: Define intricate animations, transitions, or pseudo-element styles once and apply them with a simple reference.
Global Style Management: For properties that apply broadly (e.g., reset styles, body typography), str() can centralize their definition.
Practical FSCSS Example
Let's illustrate how these methods work together in a real-world scenario within FSCSS:
/* --- 1. Defining Reusable Style Patterns with str() --- */
/* Define the base visual styling for any "card" component. */
str(cardBaseStyle, "
padding: 1.5rem;
border-radius: 8px;
background: white;
box-shadow: 0 4px 10px rgba(0,0,0,0.08);
transition: transform 0.3s ease-in-out, box-shadow 0.3s ease-in-out;
border: 1px solid #e0e0e0;
");
/* Define a common hover effect for interactive elements like cards. */
str(cardHoverEffect, "
transform: translateY(-5px);
box-shadow: 0 12px 20px rgba(0,0,0,0.15);
cursor: pointer;
");
/* Define a style for a clickable call-to-action within a card. */
str(cardCtaButton, "
display: inline-block;
padding: 0.75rem 1.25rem;
background-color: #007bff;
color: white;
border-radius: 4px;
text-decoration: none;
font-weight: bold;
margin-top: 1rem;
transition: background-color 0.2s ease;
");
/* --- 2. Applying Stored Styles (Implicit re() / Direct Injection) --- */
/* Component: Product Card */
.product-card {
cardBaseStyle /* Inject the base card styles. */
max-width: 320px;
text-align: center;
overflow: hidden; /* Ensures rounded corners are respected for content. */
&:hover {
cardHoverEffect /* Apply the hover effect when the card is hovered. */
}
.product-image {
width: 100%;
height: 200px;
object-fit: cover;
margin-bottom: 1rem;
}
.product-title {
font-size: 1.5rem;
color: #333;
margin-bottom: 0.5rem;
}
.product-price {
font-size: 1.2rem;
color: #007bff;
font-weight: bold;
margin-bottom: 1rem;
}
.add-to-cart {
cardCtaButton
/* Inject the CTA button styles. */
&:hover {
background-color: #0056b3;
}
}
}
/* Component: User Profile Widget (also uses card styling) */
.user-profile-widget {
cardBaseStyle /* Reuse the same base card styles for consistency. */
max-width: 280px;
display: flex;
align-items: center;
gap: 1rem;
background: linear-gradient(to right, #f8faff, #eef3ff); /* Override background */
.avatar {
width: 60px;
height: 60px;
border-radius: 50%;
border: 2px solid #007bff;
flex-shrink: 0;
}
.user-info {
h3 {
margin: 0;
font-size: 1.3rem;
color: #333;
}
p {
margin: 0;
font-size: 0.9rem;
color: #666;
}
}
}
How FSCSS Processes This:
During compilation, FSCSS reads the str() definitions first, populating its internal store(). Then, as it processes the actual CSS rules (.product-card, .user-profile-widget), it performs the "style replacement":
- It finds cardBaseStyle within .product-card and replaces it with the full CSS string stored under that name.
- It finds cardHoverEffect within .product-card:hover and replaces it.
- It finds cardCtaButton within .product-card .add-to-cart and replaces it.
- It finds cardBaseStyle again within .user-profile-widget and performs the same replacement.
- Finally, any specific styles defined directly within a selector (like max-width: 320px; or background: linear-gradient(...)) are added, potentially overriding or extending the injected styles based on CSS cascade rules. The resulting compiled CSS would be clean, standard CSS, effectively achieving the benefits of mixins without complex preprocessor-specific syntax in the final output. This approach empowers developers to build modular, maintainable, and highly consistent user interfaces with FSCSS, by making style patterns first-class citizens in your stylesheet architecture. fscss replacement function
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